When you’re craving a treat that perfectly marries a buttery, crumbly texture with a sharp, zesty citrus burst, look no further. We are delighted to share a recipe that we’re certain will become a staple in your kitchen: our fabulous Lemon Oatmeal Crumble Bars. We like to think of these bars as a little slice of sunshine. They bring together a wholesome oat base, a bright and tangy lemon centre, and a generous layer of irresistible crumble on top. They are wonderfully simple to prepare, an absolute pleasure to eat, and suited for any moment, from a quiet afternoon snack to a lively family gathering.

We’ve always found that the most cherished recipes are those that deliver comfort and happiness in every mouthful, and these bars certainly fit the bill. The hearty texture of the rolled oats is a perfect counterpart to the silky, tangy lemon filling, which creates a delightful sensory experience that is truly hard to resist. Whether you are an experienced home baker or a complete novice, we assure you this recipe is straightforward and yields brilliant results time and time again.

Why You’ll Love This Recipe

• A Delightful Balance of Flavours: The rich, buttery oat crumble perfectly complements the bright, sharp lemon filling. It’s a classic sweet and tart dessert that consistently wins hearts.
• Made with Everyday Staples: There is no need for a special trip to the shops. This recipe relies on common pantry ingredients like flour, oats, sugar, and lemons, making it easy to bake whenever you fancy.
• Incredibly Versatile: You can enjoy these bars as a lovely dessert after dinner, as a mid-afternoon pick-me-up with a cup of coffee, or even as a handy breakfast on busy mornings. They are a true multi-tasker.
• Ideal for Making in Advance: These bars keep exceptionally well. Feel free to prepare a batch over the weekend to enjoy all week long, or pop them in the freezer for another time. They are just as delicious, if not more so, on the second day.
• A More Wholesome Treat: Filled with the goodness of whole-grain oats, these bars are a more satisfying and nourishing choice than many other sugary confections, making them excellent healthy snack bars.

Ingredients

To assemble these wonderful bars, we will be working with two component parts: one for the oaty crumble base and topping, and another for the zesty lemon filling. This is everything you will need to have ready.

• For the Oat Crumble Base and Topping:
• 225g (2 cups) rolled oats (not instant)
• 190g (1 ½ cups) plain flour
• 200g (1 cup) light brown sugar, packed
• ½ teaspoon baking powder
• ¼ teaspoon salt
• 225g (1 cup) unsalted butter, cold and cubed
• For the Zesty Lemon Filling:
• 4 large free-range eggs
• 300g (1 ½ cups) caster sugar
• 40g (⅓ cup) plain flour
• Zest of 2 large lemons
• 120ml (½ cup) fresh lemon juice (from about 2-3 lemons)
• A pinch of salt

How to Make Perfect Lemon Oatmeal Crumble Bars

Creating these bars is a straightforward, three-stage process: we’ll first make the crumble, then mix the filling, before putting it all together for the bake. Let’s begin!

Step 1: Prepare the Crumble Base and Topping

1. Preheat and Prepare: To begin, set your oven to 180°C (160°C Fan / Gas Mark 4). Grease a 9×13-inch (23x33cm) baking tin and line it with baking parchment, ensuring you leave some paper overhanging the sides. This will help you lift the bars out later.
2. Combine Dry Ingredients: In a large bowl, whisk together the rolled oats, plain flour, light brown sugar, baking powder, and salt until they are thoroughly mixed.
3. Cut in the Butter: Add the cold, cubed butter into the dry mixture. Using your fingertips, a pastry blender, or a food processor, work the butter in until the texture resembles coarse breadcrumbs. Be careful not to overmix; small pieces of butter are what we want.
4. Form the Base: Take roughly two-thirds of the crumble mixture and press it firmly into the base of your prepared tin, creating an even layer. This will become the solid foundation for your bars. Keep the remaining third of the crumble for the topping.
5. Pre-Bake the Base: Place the tin in the oven and bake for 15 minutes, or until it turns a light golden colour. This step is key to preventing a soggy bottom.

Step 2: Create the Luscious Lemon Filling

1. Whisk the Filling: As the base is baking, you can get started on the lemon filling. In another large bowl, whisk the eggs with the caster sugar until the mixture becomes light and airy.
2. Add Remaining Ingredients: Sift the plain flour into the egg mixture, then add the salt, lemon zest, and freshly squeezed lemon juice. Continue to whisk until everything is smooth and well-combined, with no lumps of flour visible.

Step 3: Assembling and Baking Your Bars

1. Pour and Top: After its initial 15-minute bake, carefully take the base out of the oven. Pour the lemon filling evenly over the hot base.
2. Add the Crumble: Scatter the reserved crumble mixture evenly across the surface of the lemon filling.
3. Bake to Perfection: Put the tin back into the oven to bake for a further 25–30 minutes. The bars are done when the lemon filling is set (it should only have a slight wobble) and the crumble topping has turned a lovely golden-brown.
4. Cool Completely: This is a crucial step! You must allow the bars to cool to room temperature in the tin. After they have cooled, we strongly suggest chilling them in the fridge for at least 2 hours. This ensures the filling sets properly, which is essential for achieving clean, neat slices.
5. Slice and Serve: Once chilled, use the overhanging baking parchment to lift the slab from the tin. Place it onto a chopping board and cut it into bars. They are now ready to be enjoyed!

Our Top Tips for the Best Oatmeal Lemon Bars

We want you to achieve baking success. By following these straightforward tips, you can ensure your oatmeal lemon bars are flawless every single time.

• Fresh is Best: Always opt for freshly squeezed lemon juice. Its flavour is far superior and more vibrant than bottled alternatives, making a significant difference in the final product.
• Don’t Overwork the Crumble: When incorporating the butter, stop as soon as you achieve a coarse, crumbly mix. Overworking it can cause the butter to melt, leading to a tough base instead of a light and crumbly one.
• Patience is a Virtue: We understand the urge to slice into them while they are still warm, but letting the bars cool and chill completely is essential. This step is the secret to a perfectly set filling and neat, tidy slices.
• A Perfect Dessert Pairing: These bars make a wonderful conclusion to a meal, as their zesty flavour provides a refreshing contrast to richer foods. They are particularly lovely following a light main course like our Lemon Garlic Chicken, creating a delightful citrus-themed menu.

Fun Variations for Your Fruity Crumble Bars

While we adore this recipe just as it is, it also serves as an excellent foundation for other fruity crumble bars. We encourage you to get creative!

• Go Gluten-Free: You can easily make this recipe gluten-free by using a certified gluten-free plain flour blend and gluten-free oats. The final result is every bit as tasty.
• Citrus Twist: Try replacing half of the lemon juice and zest with fresh lime or orange for a different, equally delicious citrus dimension.
• Add Some Coconut: For a more tropical flavour, stir 50g of desiccated coconut into the crumble mixture before sprinkling it over the filling.
• A Hint of Spice: Incorporate a ¼ teaspoon of ground ginger or cardamom into the crumble for a subtle warmth that beautifully complements the zesty lemon.

How to Store Your Lemon Oatmeal Crumble Bars

Proper storage is key to keeping your bars tasting fresh and delicious. Here is what we recommend:

• At Room Temperature: The bars can be kept in an airtight container at room temperature for up to 2 days.
• In the Refrigerator: For extended freshness, store them in an airtight container in the fridge for up to one week. We think they taste even better when chilled!
• Freezing: These bars are brilliant for freezing. Cut them into individual portions, wrap each one tightly in cling film, and place them in a freezer-safe container. They can be frozen for up to 3 months. Thaw them at room temperature or in the fridge before serving.

Are These Healthy Snack Bars?

Although these are certainly an indulgence, they do have some wonderful qualities. The crumble features rolled oats, which are a brilliant source of dietary fibre. According to the experts at Healthline, oats can help to lower cholesterol and promote a feeling of fullness. When you bake at home, you have complete control over the ingredients, allowing you to avoid the artificial preservatives often found in shop-bought alternatives. When enjoyed as part of a balanced lifestyle that includes nutritious meals such as our healthy chicken recipes, these bars can easily fit into your diet as a mindful treat.

FAQ

Conclusion: Your New Favourite Zesty Treat

And there we have it—a simple but truly spectacular recipe for Lemon Oatmeal Crumble Bars that truly delivers. From the chewy, buttery base and the bright, tangy filling to the crunchy crumble topping, each component comes together in perfect harmony. They are an ideal make-ahead dessert, a wonderful snack, and a surefire way to add a bit of brightness to your day.

So, why not pop into the kitchen, gather your ingredients, and whip up a batch of these glorious Lemon Oatmeal Crumble Bars? We are sure they will earn a permanent place in your recipe collection. Please do leave a comment below to let us know how you got on. Happy baking!

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Prep: 20 mins
Cook: 45 mins
Yields: 16-24 bars

Ingredients

• For the Oat Crumble Base and Topping:
• 225g (2 cups) rolled oats (not instant)
• 190g (1 ½ cups) plain flour
• 200g (1 cup) light brown sugar, packed
• ½ teaspoon baking powder
• ¼ teaspoon salt
• 225g (1 cup) unsalted butter, cold and cubed
• For the Zesty Lemon Filling:
• 4 large free-range eggs
• 300g (1 ½ cups) caster sugar
• 40g (⅓ cup) plain flour
• Zest of 2 large lemons
• 120ml (½ cup) fresh lemon juice (from about 2-3 lemons)
• A pinch of salt

Instructions

1. Preheat oven to 180°C (160°C Fan). Grease and line a 9×13-inch (23x33cm) baking tin, leaving some parchment paper overhanging the sides to lift the bars out later.
2. Make the crumble: In a large bowl, whisk together the rolled oats, 190g plain flour, light brown sugar, baking powder, and ¼ tsp salt. Cut in the cold, cubed butter until the mixture resembles coarse breadcrumbs.
3. Press about two-thirds of the crumble mixture firmly into the base of the prepared tin. Bake for 15 minutes until light golden.
4. Make the filling: While the base bakes, whisk the eggs and caster sugar until light. Sift in the 40g plain flour, then add the pinch of salt, lemon zest, and lemon juice. Whisk until smooth.
5. Pour the lemon filling evenly over the hot, pre-baked base.
6. Sprinkle the remaining crumble mixture evenly over the top of the filling.
7. Bake for a further 25–30 minutes, until the filling is set (it should only have a slight wobble in the center) and the crumble topping is golden-brown.
8. Cool completely: Let the bars cool to room temperature in the tin, then chill in the fridge for at least 2 hours. This is essential for the filling to set properly for clean slices.
9. Once chilled, lift the slab out of the tin using the parchment paper, cut into bars, and serve.