Preheat your oven to 350°F. While it heats, measure out all your dry ingredients (cocoa powder, collagen, sweetener, coconut flour, baking powder, salt, and espresso powder) into a small bowl and whisk them together to break up any lumps and distribute the leavening evenly. This ensures your brownies will have an even crumb and prevents pockets of unmixed dry ingredients.

Add the cottage cheese to a food processor and blend until completely smooth, about 1-2 minutes. I like to process it for a full minute to ensure there are no grainy curds remaining, which gives the brownies a better texture. Once smooth, add the egg yolks, vanilla extract, and chocolate liquid sweetener, then blend until fully combined and creamy.

Pour the wet mixture from Step 2 into a medium bowl. Add the dry ingredient mixture from Step 1 and fold gently with a spatula until just combined, about 8-10 folds. Don't overmix—stop as soon as you no longer see dry streaks. The batter will be thick and fudgy, which is exactly what you want for dense, rich brownies.

Fold in the sugar-free chocolate chips gently using a spatula until evenly distributed throughout the batter. Pour the batter into a greased 8x8 inch baking dish, smoothing the top with a spatula to ensure even thickness. This helps the brownies bake uniformly and gives you clean edges.

Place the baking dish in the preheated 350°F oven and bake for 25-30 minutes, until the edges are set but the center still has a slight jiggle when you gently shake the pan. The brownies will continue to set as they cool, so don't overbake or they'll become dry. A toothpick inserted in the center should have some moist crumbs clinging to it, not be completely clean.

Remove the brownies from the oven and let them cool in the pan for 20-30 minutes at room temperature. I find that letting them cool completely makes slicing much cleaner and easier. Once cooled, slice into squares and store in an airtight container in the refrigerator for up to 5 days for best texture.