Preheat the oven to 350F. Spray an 911 casserole dish with cooking spray or coat with butter or coconut oil.
Heat olive oil in a large non-stick saut pan, add onion along with pinch of salt. Saut until onions are translucent. Add in peppers and garlic and cook for another two minutes.
Add in chopped spinach with a bit more salt and pepper, stir and cook until spinach has wilted down. Shut off heat and let veggies cool a bit.

In a large bowl, whisk together the eggs and then slowly stir the cooled veggie mixture into the eggs.
Pour the egg and vegetable mixture into baking dish and bake for about 30 minutes, or until the center is set and the outer edges are slightly browned. Allow the eggs to cool, then slice into six pieces.
Build the sandwiches by adding one piece of the baked eggs and one slice of cheese to each English muffin. Wrap each sandwich in plastic wrap and place into the freezer for up to 3 months.

I did mushrooms and spinach instead of bell peppers because my kids don’t like bell peppers you do you and make it your own.