Start by melting your biscoff spread until it’s runny in texture, and spread an even layer of the biscoff spread on a parchment paper-lined 8 by 8-inch baking pan. Place it in the freezer for 30 minutes or until is harden.
Preheat an oven to 180c (350f) and prep a parchment paper-lined 8 by 8-inch baking pan.
In a big mixing bowl, add the butter and the dark chocolate. Melt completely in the microwave or on a ben Marie. Let the chocolate mixture cool completely.
Add the sugar, eggs, salt, and vanilla extract. Stir with a whisk until the mixture is combined.
Sift the cocoa powder and flour into the mixture and lightly fold the dry ingredients into the wet batter. Don’t overmix! You don’t want to develop the gluten in the flour. This step ensures you have fudgy and moist brownies and not dense and dry brownies.
Pour half of the brownies batter into a parchment paper-lined baking pan, remove the biscoff spread from the fridge and peel it from the parchment paper. Place the biscoff butter on the brownie batter. (if the biscoff butter is tearing into a few pieces, it’s okay, put it together like a puzzle).
Pour the second half of the brownies batter on top of the biscoff spread and gently spread it out with a spetula until the biscoff butter is covered. Top the brownies with biscoff cookies.
Bake in a preheated oven for 30-40 minutes (depends on your oven) or until the tops of the brownies are crinkly. Make sure you line your baking pan with parchment paper to prevent the brownies to stick to the pan.