Preheat oven to 350°F. Grease a 13 x 18 inch (half sheet pan) rimmed baking sheet really well - both the bottom and the sides.
Heat 1 teaspoon of oil in skillet over medium heat. Add vegetables and cook for 3-4 minutes, until softened. Add seasonings and stir to incorporate. Set aside to cool.
In a large bowl, beat the eggs and milk together. Then add the vegetables and cheese.
Place the greased pan in the oven and then pour in the egg mixture. Bake for 18-20 minutes until the eggs are set completely.
Notes
Store any leftovers in an airtight container and refrigerate for up to 5 days.
Freeze for up to 3 months (Refer to the "How to Freeze" section)