Bring raspberries and lemon juice to a boil in a small pan over medium heat. Boil for about 5 minutes, then mash the raspberries with the back of a spoon. Remove from heat and strain raspberries to remove seeds. Return raspberry juice to heat and bring to a boil, then lower heat to a simmer for 5 more minutes. Set aside.
Pre-heat oven to 325 degrees. Line a 9x13" baking sheet with parchment paper.
In a food processor or NutriBullet, blend cottage cheese, 1 egg white, vanilla extract and Stevia until cottage cheese is smooth. Add plain and vanilla Greek yogurt, vanilla whey and remaining egg white. Blend again until smooth. Tap the bottom of the mixing bowl on the counter to release any air bubbles. Set aside.
Combine all dry brownie ingredients, then add wet brownie ingredients and mix until combined. Pour into the prepared baking sheet and spread evenly.
Gently pour cheesecake mixture on top of the brownie batter and spread evenly. Add raspberry sauce on top and swirl into a design using a toothpick or knife.
Bake at 325 degrees for 20-25 minutes or until the center of the cheesecake is mostly cooked but still a little jiggly. Refrigerate overnight before cutting and serving.
Use certified gluten free oat flour to make this recipe gluten free.