Preheat the oven to 400°F (204°C) and line a baking sheet with parchment paper.

In a large mixing bowl, whisk together the self-rising flour, unflavored protein powder, garlic powder, and salt.

Incorporate the cold cubed butter into the dry ingredients using a pastry cutter or fork until the mixture resembles coarse crumbs.

Fold the shredded cheddar cheese into the flour mixture until evenly distributed.

Add the Greek yogurt to the center and stir with a spatula until a shaggy dough forms, taking care not to overwork the gluten.

Transfer the dough to a lightly floured surface and pat down to a 1-inch thickness.

Use a 3-inch circular cutter to stamp out 8 biscuits, re-rolling scraps once if necessary.

Arrange biscuits on the baking sheet so they are just touching to encourage a vertical rise.

Brush the tops lightly with milk and bake for 12 to 15 minutes until the tops are golden brown.

Remove from oven and allow to rest for 5 minutes before serving.