These delicious and portable keto-friendly egg cups are great at room temperature, making them the perfect on-the-go snack or lunch.
Position an oven rack in the center of the oven and preheat to 400°F.
Brush 6 standard muffin cups with the butter (the butter will pool on the bottom of the cups, but that’s okay). Line each cup with a slice of prosciutto, folding and overlapping so that the entire surface of the cup is covered and no metal is peeking through. Divide the mozzarella evenly among the cups. Repeat with the Parmesan, spinach and roasted red pepper.
Whisk the eggs and cream in a large measuring cup or small pitcher; add some salt and a few grinds of pepper. Pour the egg mixture in each cup, making sure not to overfill.
Bake until the eggs are set and wobble only slightly, 10 to 12 minutes (the eggs will continue to cook after they come out). Let cool 5 minutes, then use an offset spatula to loosen the prosciutto from the edges of each cup and transfer to a plate for serving.