This Low Calorie Frittata is just 65 calories and is packed with 6g of protein per slice. It's also low carb and low sugar!I like use spinach, tomatoes, and feta in this recipe. But you can swap out the spinach for your favorite greens (kale is great in this) and the tomato for bell pepper or even squash. And you can use cheddar or pepper jack in place of the feta. Special Tip: If you don't like or can't have feta, you can swap it out for your favorite cheese. Cheddar and pepper jack cheese are also wonderful in this recipe.