Preheat an oven to 340 degrees and line an oven pan with baking sheet.
Prepare the mixture: Place flour, baking powder, sugar, salt and spices in a bowl and mix into a uniform mixture.
Place eggs, egg yolks, Biscoff Spread and liqueur in a mixer and blend them into a uniform mixture. Add the flour mixture and blend into a uniform dough. Add the chopped nuts and blend just until they are absorbed into the dough.
Design and bake for the first time: Create two cylinders from the dough approximately 10 inches long and 2.5 inches thick. Place them in the pan with a large gap between them.
Bake for 35 minutes until the rolls stabilize but are still slightly soft to the touch. During the baking they flatten considerably, and that's fine. Turn off the oven. Allow them to cool for approximately an hour-hour and a half.
Preheat the oven again to 300 degrees and line a clean pan with baking sheet.
Slice and bake for the second time: Slice the rolls into slices approximately 1/3 iches thick with a long, serrated knife (a bread knife). If you love especially long cookies, cut diagonally. Place the cookies in the pan.
Bake for approximately 20 minutes until the cookies dry and harden.
Allow them to cool and store in a sealed box at room temperature for about a week.