Preheat oven to 350°F. Spray a non-stick or silicone muffin tin with nonstick cooking spray. Heat olive oil into a a non-stick frying pan over medium high heat. Add the bell pepper and onion and saute for 2 to 3 minutes. Stir in the meat and spinach and cook an additional 2 minutes. Place 1 heaping Tablespoon into each muffin cup. Next whisk the eggs into a medium size bowl. Stir in the salt and pepper. Then pour over the meat mixture in the muffin tin, leaving 1/4" from the top. Cook for 23 to 25 minutes, or until the egg has puffed and comes clean with a toothpick. Run a knife around the edges to pop the egg frittatas out. Enjoy while hot. Store in the an air tight container in the refrigerator. Eat within 5 days.