Preheat oven to 350°F. Line a 9x9” square pan with foil or parchment paper and spray with nonstick cooking spray.

Make the brownie batter: place butter and 1 3/4 cups of the chocolate chips in a large microwave safe bowl. Heat for 1 minute on high power, stir. Continue heating in 30 second increments, stirring between each, until chocolate is melted and smooth. Stir in brown sugar and 1/2 cup granulated sugar. Stir in 3 eggs and 1 teaspoon vanilla extract, then add 3/4 cup flour, cocoa powder, and salt and mix until smooth. Set aside.

Make the cheesecake batter: beat cream cheese with a hand or a stand mixer until smooth and creamy. Add peanut butter, 1/4 cup sugar, and sour cream or greek yogurt. Mix until smooth, then add 1 teaspoon vanilla, 1 tablespoon flour, and remaining 2 eggs. Beat until smooth without lumps.

Spread half the brownie batter in the prepared pan. It’s a thick batter but should spread easily with a wooden spoon or spatula. Place half the cheesecake mixture over the top and spread carefully. If you have an offset spatula, that makes spreading this layer easier. Top with remaining brownie batter and then the remaining cheesecake to create 4 layers. Sprinkle with remaining chocolate chips.

Bake for 45-55 minutes until the edges start to get golden and the center is set. Cool completely at room temperature. Chill to set, at least 2 hours or overnight. Cut into small bars and serve. This cheesecake is very rich and a little goes a long way! Store in an airtight container in the refrigerator for up to 3 days or freeze for up to 1 month.