Preheat your oven to 180℃ (or 160℃ for fan ovens) and line an 8x8 tin with baking paper.
In a large bowl mix together the oats and brown sugar. Then add in the melted butter, the Biscoff spread and the golden syrup. Mix well until the oats are evenly coated and there are no lumps of the spread left.
Press the mixture firmly into your tin and bake for around 18-20 minutes, until golden around the edges. They will look underbaked in the centre at first but will firm up quickly as they cool.
Let them cool for around 5 minutes then use a knife to gently score lines where you plan to cut them.
Drizzle melted Biscoff spread on top then decorate with Biscoff crumbs and star sprinkles.
Leave to cool completely in the tin, around 3-4 hours. I recommend putting them in the fridge for an extra chewy texture.
Once set, remove them from the tin, cut them into slices using your score marks as a guide and enjoy!