Preheat the Oven
Set your oven to 350°F (175°C) and grease your 9-inch round cake pan.
Mix Dry Ingredients
In a mixing bowl, whisk together flour, protein powder, cocoa powder, sugar, baking powder, baking soda, and salt.
Combine Wet Ingredients
In another bowl, mix eggs, Greek yogurt, espresso, almond milk, and vanilla extract until smooth.
Combine Mixtures
Gradually add the wet mixture to the dry ingredients, stirring until just combined. Don't overmix!
Bake the Cake
Pour the batter into the prepared cake pan. Bake for 30 minutes or until a toothpick comes out clean.
Cool and Serve
Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Enjoy!