Preheat the oven to 350° F and line an 8×8 inch pan with parchment paper or spray with nonstick baking spray. Clamp down the sides of the pan with clips to hold the parchment paper in place.

In a microwave safe bowl combine the 1/2 cup butter and 6 oz chocolate. Microwave for 30 seconds at a time stirring in between until the chocolate is completely melted. Up to 90 seconds total. Let the chocolate cool for 5 minutes.

Add in 3 eggs and whip using a whisk or the whisk attachment on high speed for 2 minutes.

Add in only 1 cup sugar and whip again for 1 minute.

Switch to a spatula and add in only 1 teaspoon vanilla mix until combined. Next add in the 1/2 cup flour, 1/4 cup cocoa powder, and 1/2 tsp kosher salt. Mix until combined. Set aside.

In a medium sized bowl add the cream cheese and remaining ¼ cup sugar and whip on medium speed with a hand mixer for 1 minute until smooth.

Add in the egg white and ½ tsp vanilla extract and mix with a rubber spatula until combined.

Pour the chocolate brownie batter into the prepared 8x8 pan and pour the cream cheese mixture on top. Smooth it out with a spoon and then swirl the two batters with a knife.

Bake for 35-38 minutes until the edges of the cheesecake brownies are set and the middle is just a tiny bit jiggly.

Cool completely before cutting and serving.