The fudgiest brownies, tall and decadent, with a Biscoff cookie crust, a generous swirl of Cookie Butter woven into the batter, and a thick layer of Cookie Butter Frosting on top. Featuring three appearances of Biscoff and Cookie Butter, these Cookie Butter Brownies with Cookie Butter Frosting are a dream!
Line a 9-inch square pan with foil, allowing it to hang over the edges. Lightly coat with nonstick spray.
Crush the Biscoff cookies into fine crumbs. I will either use my food processor to accomplish this, or sometimes I put the cookies in a gallon-sized Ziploc bag, and I do some light smashing with a rolling pin.
Set aside approximately 1/4 cup cookie crumbs for garnish.
In a medium bowl, combine remaining cookie crumbs, butter, and sugar.
Press into the bottom of the prepared pan.
In a large bowl, whisk together melted butter, sugar, and vanilla.
Add the eggs, one at a time, whisking well after each addition.
Stir in the cocoa powder, flour, and salt, mixing until just blended.
Spread the brownie batter evenly over the crust.
Place the cookie butter in a small heatproof bowl. Heat for 20-30 seconds, or until melted and thinned. Heat at additional 10 second intervals as needed.
Drizzle the melted cookie butter over the brownie batter, and lightly swirl with a knife.
Bake at 350 degrees for 40-45 minutes, or until edges and center appear set, and a toothpick inserted near the center comes out mostly clean, with only a few moist crumbs.
Cool in the pan on a wire rack.
Once completely cool, run a knife around any exposed edges. Carefully lift the brownies out by the foil overhang.
Transfer to a plate or serving platter.
In a large mixing bowl, beat butter and cookie butter until smooth.
Add powdered sugar, beating until smooth.
Beat in vanilla.
Add heavy cream, one tablespoon at a time, beating until frosting is light and fluffy. It should be thick, but fluffy and spreadable.