Preheat oven to 375°F. Brown chorizo in a skillet over medium, breaking it up; drain excess fat.
Sauté onion and peppers in the same skillet until softened, about 5 minutes. Stir in cumin and paprika.
Spread frozen tater tots in a greased 9x13 pan in an even layer.
Scatter cooked chorizo and pepper mix over the tots. Sprinkle 1 cup cheese on top.
Whisk eggs, milk, salt, and pepper. Pour evenly over the casserole.
Top with remaining 1 cup cheese. Bake 35–40 minutes until set and golden.
Let rest 5 minutes, then sprinkle cilantro if using and slice to serve.