Preheat oven to 400 degrees Fahrenheit (204 degrees Celsius) and line a baking sheet with parchment paper.

In a large mixing bowl, whisk together the flour, protein powder, baking powder, and salt until evenly distributed.

Incorporate the cold butter into the dry mixture using a pastry cutter until it reaches a coarse crumb consistency.

Gently fold in the Greek yogurt, skim milk, and liquid egg whites until a cohesive dough forms.

Turn the dough onto a lightly floured surface and fold it over itself 3 to 4 times to develop layers without overworking the protein.

Pat the dough to a 1-inch thickness and cut into 8 circular biscuits using a 3-inch cutter.

Arrange the biscuits on the baking sheet and bake for 18 to 22 minutes until the tops are golden brown.

Transfer to a wire rack and allow to cool completely before storing in an airtight container.