Preheat your oven to 375°F (190°C). In a large mixing bowl, combine all-purpose flour, baking powder, salt, and garlic powder. Cut in the cold cubed butter until the mixture resembles coarse crumbs.
Stir in the shredded cheddar cheese followed by buttermilk. Mix until just combined.
In another large bowl, whisk together eggs, milk, salt, black pepper, and onion powder until fully blended.
Grease a baking dish and layer half of your biscuit dough at the bottom. Pour half of the egg mixture over it. Sprinkle crumbled turkey bacon and additional shredded cheddar cheese before pouring the remaining egg mixture on top. Top with dollops of remaining biscuit dough.
Place your assembled casserole into the preheated oven and bake for about 35 minutes or until golden brown on top and set in the middle.