Heat oven to 425°F. Whisk together Krusteaz Buttermilk Pancake Mix, salt and garlic powder.
Using a fork or pastry blender, cut in cold butter until butter is incorporated and mixture is crumbly.
Stir in sausage, cheese, onion onions. Add 3/4 cup buttermilk and stir until dough just comes together. Add more buttermilk, 1 tablespoon at a time, as needed. Dough will be sticky.
Using a #20 scoop (rounded 3 tablespoons), scoop dough onto lightly greased or parchment-lined baking sheet. Place in freezer for 15 minutes or the biscuits can be frozen until ready to bake.
Brush tops of biscuits with egg wash. Bake for 14-18 minutes. Serve warm.