Preheat oven to 400 degrees.Heat a skillet over medium-high heat and add in olive oil. Once hot, add peppers and onions and cook for about 4 minutes, or until tender.In a large bowl, whisk together eggs and milk and season with salt and pepper.Prepare an 8x8 baking dish by spraying with cooking spray and begin layering casserole by spreading ham along bottom of dish.Top with cooked peppers and onions and then sprinkle with cheese.Finally, pour eggs on top.Bake until eggs are fully cooked and fluffy, about 25-30 minutes.Top with a little extra cheese, chives, sour cream, avocado, or salsa, if you wish!Enjoy!