Brownie Layer:

Place 1/2 cup of semisweet chocolate and butter in a microwave-safe bowl and microwave on medium (50 percent power) for 1 minute or until melted. Stir until well-combined and set aside to cool slightly.

Spray an 8 x 8 x 2 inch baking pan with non-stick cooking spray. Line the pan with parchment paper, covering the bottom and sides of the pan.

With a mixer on low speed, or by hand, beat eggs and sugar until combined and light yellow. Slowly pour in melted chocolate. 

Add potato starch, cocoa powder, salt and vanilla and mix together. Stir in 1/2 cup chocolate chips. 

Spread batter into prepared pan.Preheat oven to 350 degrees. 

Cream Cheese Layer:

Beat cream cheese with mixer on medium speed until smooth. Add sugar, egg and vanilla, and beat until mixture is smooth and creamy.

Pour cream cheese mixture on top of brownie batter. Drag a knife through the batter several times to create a marbled design.

Bake for 35 minutes, until the brownies feel firm to the touch and a toothpick inserted into the middle of the brownies comes out clean. 

Cool completely in the pan. When cool, lift the brownies out of the pan by the edges of the parchment paper. Place on a cutting board and cut into 25 small squares.