Preheat oven to 350˚F. Grease a 3 quart casserole dish with cooking spray.
Melt butter in a medium skillet over medium-high heat. Once melted, add onion and cook until tender, stirring frequently, about 2 to 3 minutes. Remove from heat.
Cut each biscuit into 8 even pieces. Place in the bottom of the casserole dish.
In a large bowl, whisk together eggs, milk, pepper, cumin, paprika, chili powder, garlic powder, and cayenne pepper until well-combined. Stir in bacon, onion, and 1/2 cup cheese. Pour the egg mixture over the biscuits in the pan. You may need to spread the mixture around slightly over the top to evenly distribute the cheese and bacon.
Bake for 35 to 40 minutes. The edges should be golden and the center should be set. Top with remaining cheese and return to the oven for 2 to 3 minutes until cheese is melted.
Remove from oven and let rest for 5 minutes before topping with chopped avocado. Serve immediately with recommended toppings, as desired.