Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan for even baking.
In a large bowl, cream together the softened butter, peanut butter, and Swerve Sweetener until light and fluffy, about 2-3 minutes.
Beat in the eggs one at a time, ensuring each is fully incorporated, then stir in the vanilla extract.
In a separate bowl, whisk together the almond flour, whey protein powder, coconut flour, baking powder, and salt thoroughly.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined to avoid overmixing.
Pour the batter into the prepared 9x13 inch baking pan and spread evenly with a spatula.
Bake for 25-30 minutes, or until a wooden skewer inserted into the center comes out clean. Let cool completely before frosting.