Cookie butter (aka Biscoff spread, Speculoos, and various store brands) creates luscious bars with some macadamia nuts added for crunch! These thick bars will store well at room temperature for as long as a week, if they last that long.
Preheat oven to 350-degrees. Line a 9x13 pan with aluminum foil and apply nonstick spray.
In a large bowl, cream butter until light and fluffy. Add in both sugars, followed by the eggs one by one, then the vanilla.
In a separate bowl, sift together the flour, salt, and baking powder. Gradually mix into the wet ingredients until just incorporated.
Spread half of the dough in the bottom of the pan. Mixture will be thick. Use an uneven spatula to spread 2/3 cup cookie butter in an even layer over the dough.
Top with remaining dough and spread to edges. Dollop the 1/2 cup of cookie butter here and there over the top, then use a butter knife to swirl it into the dough.
Bake for 40 to 45 minutes, until the top is golden brown and the middle passes the toothpick test. Dough will rise a great deal.
Cool completely in pan. Use the foil to lift up bars for easy cutting. Store sliced pieces in a sealed container at room temperature for as long as a week.
OM OM NOM!