1-First, preheat your oven to 350 degrees Fahrenheit and place a rack in the center. Generously grease a standard 12-cup muffin tin with nonstick spray to avoid any sticking issues. Evenly divide the chopped spinach, red and green bell peppers, and tomatoes among the muffin cups, filling them about two-thirds full.

2-Next, in a large bowl or measuring cup with a spout, whisk together the eggs, egg whites, salt, basil, oregano, and pepper until fully combined. Carefully pour the egg mixture into each muffin cup, filling about three-quarters full. Sprinkle crumbled feta cheese evenly over the tops for that extra flavor kick.

3-Then, bake for 24 to 28 minutes until the muffins are set. Let them cool for a few minutes before running a butter knife around the edges to loosen and remove from the pan. Serve immediately or cool completely before storing in the refrigerator or freezer for later use.