Preheat oven to 425°F (218°C) and line a baking sheet with parchment paper.

In a large mixing bowl, whisk together flour, protein powder, baking powder, baking soda, and salt.

Incorporate cold butter into the flour mixture using a pastry cutter or fingers until it resembles coarse crumbs with pea-sized pieces.

Fold in the shredded cheddar cheese and chopped chives.

Add Greek yogurt and milk, stirring with a wooden spoon until a shaggy dough just begins to form.

Transfer dough to a lightly floured surface and gently pat into a rectangle approximately 1-inch thick.

Cut out 12 rounds using a 2.5-inch biscuit cutter, pressing straight down without twisting.

Arrange biscuits on the baking sheet so they are barely touching.

Bake for 12 to 15 minutes until the tops are golden brown and the biscuits have risen.

Cool on a wire rack for 5 minutes before serving.