Preheat oven to 325°F.

Line a 9×13 pan with nonstick foil.

In a saucepan over medium heat, melt the butter.

Then add sugar stirring until dissolves.

(Aim for 120 degrees)

Remove heat.

In a bowl, whisk together the eggs, cocoa powder, baking powder, salt and vanilla.

Add the warm butter mixture and continue whisking until mostly smooth.

Stir in the flour and set aside.

Beat cream cheese and sugar together on medium speed.

Add vanilla, sour cream and eggs.

Spread 2/3 of the brownie batter into the prepared pan.

Spoon the cheesecake mixture on top of the brownie batter, and spread evenly on top.

Drop dollops of the remaining brownie batter on top of the cheesecake layer.

Using a butter knife to swirl the layer together.

Bake for 35-40 minutes, until the top is set.

Cool and chill a few hours before cutting into bars.

Serve with hot fudge.