Preheat oven to 350F (180C). Line the bottom of an 8-inch (20 cm) square baking pan with parchment paper. Grease the parchment with butter, set aside.
Chop the chocolate and transfer into heat proof bowl, add butter and set the bowl over a double boiler (a pot with simmering water). Melt completely and set aside to cool slightly.
In a large bowl place white sugar, brown sugar, eggs, salt and vanilla extract. Beat until light and fluffy.
Slowly pour in chocolate mixture while constantly mixing. Mix until combined and smooth.
Sift int flour and cocoa powder. Fold just until combined. Do not over mix.
Pour half of the batter, then scoop 3-4 tablespoons of Biscoff spread. Pour the remaining batter and scoop another 4-5 tablespoons of Biscoff on top.
Arrange 8 lotus cookies on top of the batter.
Bake for 25-30 minutes.
Allow to cool slightly, then cut into bars/squares.
All baking tools I am using in this recipe are here