Preheat the oven to 350°F (175°C).
Grease an 8×8-inch or 9×9-inch baking dish.
In a blender or food processor, combine the cottage cheese and eggs until smooth and creamy.
Transfer the blended mixture to a mixing bowl.
Add the almond flour, sweetener, vanilla extract, lemon zest, and baking powder to the bowl.
Stir until all the ingredients are well incorporated.
Gently fold in the mixed berries.
Pour the batter into the prepared baking dish and spread it evenly.
Bake for 35–40 minutes, or until the top is lightly golden and the center is set.
Allow the berry bake to cool for 20–30 minutes before slicing.