Preheat oven to 400°F. Whisk the eggs, milk, garlic, and salt until well combined.
Heat 1/2 tbsp olive oil in a large oven-safe skillet (10-12 inch) over medium heat. Add the red pepper. Sauté until the pepper has softened a bit, about 5 minutes. Add the spinach and sauté until the spinach has wilted. Stir the veggies around evenly in pan, and then add the egg mix, tilting the pan if necessary to make sure it's evenly spread. Sprinkle with the shredded cheese and bake for 15-20 minutes, or until the eggs are set. Season with any extra salt and pepper to taste, serve hot.