Preheat your oven to 375° Fahrenheit. Lightly grease a 9x13 inch baking dish.
SAUSAGE AND VEGETABLE MIXTURE
In a pan over medium heat, brown the breakfast sausage. Remove the sausage with a slotted spoon, leaving the juices in the pan.
Using the same pan, sauté the onions and bell peppers until soft, then add thawed hash browns and cook until lightly browned. Add the sausage back into the skillet and remove from heat.
EGG MIXTURE
In a large bowl, whisk the eggs, milk, salt, and pepper until well combined.
ASSEMBLE - Layering the Lasagna
Spread a small amount of the egg mixture into the casserole dish. Add a layer of lasagna noodles, sprinkle with the sausage mix, a third of each cheese, and fill with a third of the egg mix. Repeat and make three layers.
Bake
Cover with foil and bake for 30 minutes. Remove the foil and bake for an additional 15-20 minutes until the lasagna is golden and set.
Let it rest for 10 minutes before slicing and serving.