Preheat oven to 375 degrees. Add sausage, peppers, and onions to a large non-stick skillet over medium-high heat. Cook and crumble the sausage until browned and vegetables are tender.
Drain grease if needed. Add Rotel tomatoes to pan and stir to combine. Remove from heat and set aside.
In a medium bowl, whisk eggs with milk, cumin, chili powder, salt, and pepper. Add shredded cheese and stir to combine.
Spray a 9×13 baking pan with cooking spray. Add bagel pieces. Add sausage mixture evenly over the top. Pour egg mixture on evenly.
Cover with foil and bake for 20 minutes. Remove foil and bake for an additional 10-15 minutes until browned. Allow to sit for 5 minutes then garnish with cilantro before serving.