Prepare the Filling: Line a small baking tray or plate with parchment paper. Drop 12 teaspoon-sized dollops of Biscoff spread onto the paper, spacing them out. Place the tray in the freezer for at least 1 hour, or until the dollops are completely solid.

Cream Butter and Sugars: In a large bowl or the bowl of a stand mixer, beat the softened unsalted butter, caster sugar, and soft light brown sugar together on medium speed for about 3-4 minutes, until the mixture is light, pale, and fluffy.

Add Wet Ingredients: Add the room temperature egg and vanilla extract to the butter mixture. Beat again for another minute until everything is well combined. Scrape down the sides of the bowl to ensure it's all incorporated.

Combine Dry Ingredients: In a separate bowl, whisk together the plain flour, bicarbonate of soda, baking powder, and salt. This ensures the raising agents are evenly distributed.

Make the Dough: Add the dry ingredients to the wet ingredients in two batches, mixing on a low speed until just combined. Be careful not to over-mix. If you're using chocolate chips, fold them in now with a spatula.

Chill the Dough: Cover the bowl with cling film and place it in the refrigerator to chill for at least 30 minutes. This makes the dough less sticky and easier to handle when stuffing.

Assemble the Cookies: Once chilled, take the dough out of the fridge and the Biscoff dollops out of the freezer. I find that using a medium ice cream scoop helps to portion the dough evenly. Scoop out about 2 tablespoons of dough, flatten it into a disc in your palm, place one frozen Biscoff dollop in the centre, and carefully wrap the dough around it, rolling it into a smooth ball. Ensure the filling is completely sealed inside.

Final Chill & Preheat: Place the stuffed cookie dough balls onto a parchment-lined baking tray, spacing them well apart (I usually fit 6 per tray). Put the tray back in the fridge for another 30 minutes. While they chill, preheat your oven to 180°C (160°C fan).

Bake to Perfection: Bake the chilled cookie balls for 12-14 minutes. They are ready when the edges are a light golden brown and the centres look slightly underdone. Don't overbake them if you want a soft, gooey centre.

Cool Down: Let the cookies cool on the baking tray for 10 minutes before transferring them to a wire rack to cool completely. This allows them to set properly. The centre will be incredibly molten when warm!