Preheat oven to 375F. Spray muffin tin with olive oil.
Heat a pan over medium-high heat and cook the chopped pepper and kale until soft, about 4 minutes.
In a large bowl, crack eggs or egg whites and whisk eggs until smooth, about one minute.
Add sauteed peppers and kale, optional mozzarella, salt, pepper, and garlic powder and stir to combine.
Bake for 18-20 minutes, or until eggs are set and tops are golden.
Serve immediately with diced tomatoes and avocado or store in the refrigerator for 5 days or in the freezer for 2 months.