Microwave the butter and chocolate until the chocolate is fully melted. Add the cocoa powder and stir until completely dissolved. Let it cool.

Beat the eggs with the sweetener and salt until fluffy. Add vanilla extract (optional).

Add the melted mixture and stir until combined.

Add the almond flour and beat until well mixed. Gradually sprinkle in the xanthan gum while mixing. Once well combined, let the mixture thicken slightly. Pour into a 9x9-inch pan lined with parchment paper, saving a little for the marble effect. Tap the pan on the counter 2-3 times.

Beat the cream cheese with the sweetener until smooth. Add the egg and beat until combined.

Spoon the cream cheese mixture over the brownie batter one spoonful at a time, smoothing it out gently. If you pour it all at once, it will sink. Use the reserved brownie batter to drop small amounts on top. Use a toothpick to create a marbled pattern as desired. Bake at 320°F (160°C) for about 30-35 minutes, depending on your oven.