Add the cottage cheese, egg, cocoa powder, sweetener, peanut butter, salt, and vanilla extract to a blender. Blend on medium-high speed for 1-2 minutes until the mixture is completely smooth with no lumps or cottage cheese curds visible. I find that taking an extra 30 seconds to ensure smoothness makes a huge difference in the final texture—lumps will create an uneven, grainy brownie. Scrape down the sides of the blender if needed to ensure everything is fully incorporated.

Line a 8x8 inch baking dish (or similar size small baking pan) with parchment paper, leaving slight overhang on two sides for easy removal. Pour the batter from Step 1 into the prepared dish and smooth the top with a spatula for even cooking. The parchment paper makes removal effortless once cooled, and I always prefer this method over greasing since these brownies are delicate.

Bake in a preheated 350°F (180°C) oven for 24-26 minutes, or use an air fryer at 320°F (160°C) for 19-22 minutes if you prefer. The brownies are done when a toothpick inserted in the center comes out with just a few moist crumbs—they will continue to firm up as they cool. These brownies are naturally dense and fudgy due to the cottage cheese base, so don't overbake or they'll become dry.

Remove the brownies from the oven or air fryer and let them cool at room temperature for about 15-20 minutes until they're no longer steaming. Transfer to the refrigerator and chill for at least 30 minutes—this cooling time is essential for the brownies to set properly and become easier to cut into clean squares. Once chilled, lift the brownies out using the parchment paper overhang and cut into 9-12 pieces depending on your desired size.