Cook the filling. In a skillet over medium heat, sauté the diced onion and bell peppers in a little oil for 3–4 minutes until softened. Add the crumbled sausage and stir to combine. Set aside.

Scramble the eggs. Whisk together eggs, milk, garlic powder, salt, and pepper. Melt butter in the same skillet over medium-low heat. Add the egg mixture and scramble gently, pulling the curds slowly. Remove from heat while still slightly underdone — they'll finish cooking when you reheat the quesadillas.

Assemble. Lay a tortilla flat. On one half, layer a scoop of egg mixture, a spoonful of the sausage and veggie mix, and a generous handful of cheese. Fold the tortilla over.

Toast. Lightly spray a clean skillet or griddle over medium heat. Cook each quesadilla for 2–3 minutes per side until golden brown and the cheese is melted. Don't press too hard — you want some fluffiness in there.

Cool completely before storing. This prevents sogginess.