Preheat oven to 350 degrees.

Grease a 9"x13" pan.  Line the pan with parchment paper and grease the parchment.

For the brownie batter:  Melt the butter, in a large saucepan over medium heat.  Add the 2 cups of sugar and bring to a low boil, stirring continually until the sugar has dissolved (about 5 minutes).

Take the pan off the heat and add the cocoa, salt, baking powder, and vanilla and stir until combined.  Let the mixture cool for about 5 minutes.

Whisk the eggs in, one at a time, and then the gluten free flour and xanthan gum.  Stir the mixture until smooth.

For the cream cheese batter:  With a hand mixer, beat the cream cheese until no large chunks remain.

Add in the sugar, flour, vanilla, half & half, and eggs and mix until smooth.

Stir the chocolate chips into the brownie batter.

Spread half the brownie batter on the bottom of the pan, then pour the cream cheese batter over the top.

Drop the remaining brownie batter by spoonful onto the cream cheese layer.  Using a table knife or spatula, swirl the brownie batter together with the cream cheese batter to create a marbled look.

Bake the brownies for 45-55 minutes, until a wooden pick inserted into the center comes out clean.

Remove from the oven and cool completely before cutting.