Cookie butter—an addictive spread made from spiced speculaas cookies—makes these blondies (adapted from the Biscoff recipe archives) tender and dense with a nuttiness that reminds me a little of almond butter. Feel free to use any kind of chocolate you like; chopped toasted nuts (like pistachios) would also be really good. —Posie (Harwood) Brien
chocolate chips (I use a mix of semisweet and white chocolate, but any type works)
Preheat your oven to 325°F. Grease a 9-inch square (or an 8-inch square) baking pan and line the pan with parchment paper or foil.
Melt the butter, and set aside to cool slightly (it doesn't need to cool fully, it just shouldn't be hot).
In a large bowl or a stand mixer, combine the melted butter, sugar, eggs and egg yolk, cookie butter, vanilla, and salt. Mix until smooth and well-combined (if your cookie butter is very thick and stiff, it helps to heat it for a few seconds in the microwave so it's easier to incorporate).
Add the flour and baking powder and mix until just combined. Mix in the chocolate chips.
Pour the batter into your prepared pan and smooth the top. Bake for 30 minutes (if using an 9-inch square pan) or 40 minutes (if using an 8-inch square pan). The bars should start to brown on the edges and a tester inserted in the center should come out clean, or with just a few moist crumbs clinging to it.
Remove from the oven and let cool fully before lifting out of the pan and slicing.