Prep the pan: Heat the oven to 350°F (175°C).
Generously grease a 12-cup muffin tin with cooking spray or butter. Make sure you coat the sides so the egg cups release easily.
Sauté the aromatics (optional but tasty): If using fresh garlic and spinach, warm the olive oil in a skillet over medium heat. Cook the garlic for 30 seconds until fragrant, then add the spinach and sauté just until wilted.
Let it cool slightly.
Whisk the eggs: In a large bowl, whisk the eggs with the cream until smooth. Stir in the Parmesan, salt, pepper, and red pepper flakes. Fold in the parsley or chives.
Add the mix-ins: Gently fold in the cooled spinach and the bacon or ham, if using.
If you skipped the sauté, add the minced garlic directly now or use garlic powder.
Fill the cups: Divide the mixture evenly among the muffin cups. Aim for about three-quarters full. Sprinkle a little extra Parmesan on top for a golden, cheesy crust.
Bake: Place the tin on the middle rack and bake for 16–20 minutes, or until the centers are set and the tops look slightly puffed and lightly golden.
A toothpick inserted in the center should come out mostly clean.
Rest and release: Let the egg cups sit in the pan for 3–5 minutes. Run a thin knife around the edges to loosen, then lift them out gently.
Finish and serve: Top with a pinch of fresh herbs and a small shower of Parmesan if you like. Serve warm with toast, avocado, or a simple side salad.