In a medium bowl, beat the softened cream cheese with the Swerve Confectioners until smooth. Beat in the egg, lemon zest, and lemon extract until well combined. Set aside.

In a large bowl, whisk together the almond flour, Swerve Granular, whey protein powder, baking powder, and salt.

Add the wet ingredients to the dry ingredients and mix until just combined. Do not overmix.

Spoon half of the batter into a greased 8x8 inch baking pan. Drop spoonfuls of the cream cheese mixture over the batter, then top with the remaining cake batter.

Using a knife or skewer, gently swirl the cream cheese through the cake batter to create a marbled effect.

Bake at 350°F (175°C) for 35-40 minutes, or until a toothpick inserted into the center comes out clean and the top is golden brown. Cool completely before slicing and serving.