In a large skillet, cook bacon over medium heat until crisp. Remove from skillet and drain on paper towels. Crumble bacon and set aside.
Leave 1 tablespoon bacon drippings in skillet (saving remaining for other use). Sauté green onions in bacon fat for 2 minutes, set aside.
Preheat oven to 425°F. Line a large baking sheet with parchment paper and set aside. In a bowl, whisk together the buttermilk and egg. Set aside.
In a bowl whisk together the flour, baking powder, garlic powder, and red pepper flakes. Using a pastry blender or fork, cut in butter until mixture resembles coarse crumbs. Mix in crumbled bacon, green onions, and shredded cheese. Make a well in the center of the flour mixture.
Reserve 2 tablespoons of the buttermilk mixture, set aside to brush on biscuits later. Add remaining buttermilk mixture to flour mixture. Using a fork, stir just until mixture is moistened.
With your hand, knead dough by folding and gently pressing it for 10 to 12 folds or just until dough holds together in bowl. Roll out dough evenly to 1/2-inch thickness. Using a 2- to 2-1/2-inch round cutter, cut rounds from the dough. Place rounds, nearly touching, on prepared baking sheet. Brush rounds with reserved 2 tablespoons buttermilk mixture. Top each biscuit with sprinkle of Maldon Smoked Sea Salt Flakes (optional).
Bake about 15 minutes or until golden brown. Transfer biscuits to wire racks to cool completely. Serve as is or with butter.