Brown the Sausage: In a large skillet over medium-high heat, brown the halal beef breakfast sausage, breaking it apart with a wooden spoon into small crumbles until cooked through (approx. 6–8 minutes). Drain any rendered fat on paper towels.

Prep the Slow Cooker: Spray a 6-quart oval slow cooker insert thoroughly with non-stick olive oil or butter spray to ensure clean slicing later.

Layer Hashbrowns & Fillings: Spread half of the thawed shredded hashbrowns across the bottom. Layer half the browned beef sausage, half the diced bell peppers, half the red onion, and 1.5 cups of the mixed shredded cheeses. Repeat with the remaining hashbrowns, sausage, veggies, and 1 cup of cheese (reserve the remaining 1/2 cup for the finish).

Whisk the Custard: In a large bowl or glass pitcher, vigorously whisk the 12 eggs, whole milk, garlic powder, smoked paprika, kosher salt, and black pepper until light, frothy, and uniform.

Pour Custard Evenly: Slowly pour the egg mixture evenly over the casserole layers, allowing the custard to seep down through the hashbrowns and sausage.

Slow Cook to Tender Perfection: Cover with the lid. Cook on LOW for 4 to 5 hours (or on HIGH for 2.5 to 3 hours) until the center is set and edges are golden. Sprinkle the reserved 1/2 cup of cheese on top during the final 20 minutes until melted and molten.

Rest, Garnish & Serve: Turn off the slow cooker and let rest uncovered for 10 minutes so the casserole sets firmly into sliceable portions. Garnish with fresh chives and serve warm with coffee and fresh fruit!