Preheat your oven to 375°F (190°C). This ensures that your casserole bakes evenly and comes out perfectly golden.
In a skillet over medium heat, cook the breakfast sausage until it is browned and fully cooked. Break it up into small pieces while cooking. Once done, set it aside to cool slightly.
Open the can of refrigerated biscuits. Cut each biscuit into quarters. This will allow them to puff up and create those delightful 'bubbles' in the casserole.
In a large mixing bowl, whisk together the eggs and milk. If you’re using garlic powder, add it to the mixture now for an extra flavor boost. Season with salt and pepper to taste.
Add the cooked sausage, biscuit pieces, cubed Velveeta, and shredded mozzarella to the egg mixture. Stir gently until everything is well combined and coated in the egg mixture.
Pour the mixture into a greased 9x13-inch baking dish. Spread it out evenly, and then pop it in the preheated oven. Bake for 30-35 minutes, or until the top is golden brown and the casserole is set in the middle.
Once baked, remove the casserole from the oven and let it cool for a few minutes. Cut it into squares and serve it warm. Enjoy the cheesy, savory goodness with your favorite breakfast condiments!