In a mixing bowl, combine the protein powder, baking powder, cinnamon, and your chosen sweetener. Whisk these dry ingredients together until evenly blended and free of clumps.

Crack two eggs into the dry mixture, followed by the almond milk. Use a whisk or electric mixer to blend until the batter is smooth and creamy.

Grease a small baking pan. Pour half of your batter into the pan and sprinkle cinnamon over this layer. Spoon the remaining batter on top and use a knife to lightly swirl it together.

Preheat your oven to 350°F (175°C). Bake for about 12 minutes, or until the center is firm and a toothpick inserted comes out clean.

Once baked, remove the pan and allow the cake to cool for a few minutes before slicing.