Preheat the oven to 350°F
In a large bowl, combine the melted butter, eggs, cookie butter, and vanilla together.
Mix until fully combined.
Mix in the white & brown sugars.
Add in the flour, baking powder, baking soda, nutmeg, & salt. Combine until all the flour is dissolved & a thick batter forms.
In a 8×8 square pan, evenly spread out the batter. Top off the batter with chopped biscoff cookies.
Bake the blondies for 24-25 minutes.
Let the blondies cool in the pan for 10-15 minutes before removing & cutting.