Preheat your oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper.
Make the brownie batter first. In a medium bowl, whisk the melted butter and monk fruit sweetener together. Add the egg and vanilla extract and whisk until smooth. Add the almond flour, cocoa powder, baking powder, and salt. Stir until a thick, dark chocolate batter forms. Set aside.
Make the blondie batter. In another medium bowl, whisk the melted butter and monk fruit sweetener together. Add the egg and vanilla extract and whisk until combined. Add the almond flour, baking powder, and salt. Stir until a thick, golden batter forms. Fold in the sugar-free chocolate chips.
Drop alternating spoonfuls of the brownie and blondie batters into the prepared pan, creating a checkerboard pattern across the bottom.
Use a toothpick to gently swirl the two batters together, dragging through them just 3 or 4 times. Do not over-swirl as you want a dramatic contrast between the dark and light batters.
Bake for 24 to 28 minutes, until both batters are set and a toothpick inserted in the center comes out with just a few moist crumbs. The brownie sections will look fudgy and the blondie sections golden.
Let cool completely in the pan before slicing into 16 squares. Each piece will have a stunning swirl of both brownie and blondie, making these incredibly photogenic and delicious.
