Prepare the ingredients for the brownie layer. Preheat the oven to 340°F (170°C). Grease a square baking pan, approximately 8x8 inches, with butter, line with parchment paper, and grease again with butter and flour. Place the bittersweet chocolate, butter, and powdered sugar in a bowl.

Heat in the microwave in 30-second intervals, stirring after each, until melted and combined. Let it cool slightly so the eggs don't cook when added. Add the eggs and vanilla.

Stir until the mixture is smooth and shiny. Add the flour and cocoa powder.

Mix well; it will be a thick batter. Pour into the prepared pan and spread carefully to cover the bottom evenly.

Prepare the ingredients for the cheesecake mixture. Using a mixer or by hand with a flexible spatula, beat the cream cheese. Add the sugar and vanilla until everything is combined.

Beat the egg and add it to the mixture. Stir well to combine.

Finally, add the flour and orange zest and mix to combine. Drop by spoonfuls onto the brownie layer in the pan.

Use a knife to swirl and create a marbled effect. Bake for 30 minutes or until a toothpick comes out clean, being careful not to burn. Let cool completely in the pan, preferably refrigerate for about two hours before cutting. Remove from the pan using the parchment paper, and place on a cutting board.

Cut into 12 squares or make them smaller, as I did, cutting into 36 bite-sized pieces. To ensure clean cuts, use a very sharp knife and clean it after each cut. Keep refrigerated until serving. Delicious!