Start by lining a square baking tray with parchment paper.
Melt the Biscoff spread and pour it into the prepared tray. Place the tray in the freezer to set.
Preheat your oven to 350°F (180°C).
In a bowl, stir together the oats, flour, sugar, and baking powder.
Melt the butter in the microwave and mix it into the dry ingredients until well combined.
Take the tray with the frozen Biscoff out of the freezer.
Press about two-thirds of the crumble mixture into the base of the tray, covering it evenly. Layer the frozen Biscoff on top.
Sprinkle the remaining crumble mixture over the Biscoff layer.
Bake for 40 minutes or until golden and crispy on top.
Let the bars cool completely before removing them from the tray and cutting them into squares. Enjoy!