Dice potatoes. Bring potatoes to a boil and cook 5 minutes. Drain and set aside to cool.
Heat a large skillet over med/high heat and brown sausage, breaking up the meat as it’s cooked. Remove sausage.
In the same skillet, add 1 tsp oil and the onions, peppers and mushrooms. Sautee until vegetables are slightly tender. Add garlic and mix and set aside to cool.
Whisk together the eggs, half and half and season with salt and pepper.
In a bowl, combine the potatoes, sautéed vegetables and sausage, egg mixture and 1 cup of cheese. Mix.
Transfer to a baking dish.
Cover baking dish with foil. Bake in a preheated oven to 375°F covered 30 minutes.
Uncover, lightly mix ingredients, top with remaining cheese and bake another 10-15 minutes.