Preheat the oven: Set your oven to 350°F (175°C). Grease a 12-cup muffin tin generously with olive oil spray or butter so the muffins release cleanly.
Prep the mix-ins: Dice the ham and veggies into small, even pieces.
Smaller pieces spread more evenly and cook better in the short bake time.
Whisk the eggs: In a large bowl, whisk the eggs with the milk (if using) until smooth and slightly frothy. This adds air and makes the muffins fluffier.
Season well: Add salt, pepper, garlic powder, onion powder, and smoked paprika. Stir to combine so the seasoning is evenly distributed.
Stir in the fillings: Fold in the ham, cheese, bell pepper, green onion, and parsley.
Mix gently so every cup gets a good balance.
Fill the muffin tin: Divide the mixture evenly among the 12 cups, filling each about 3/4 full. Give the pan a light tap on the counter to settle the mixture.
Bake: Place on the middle rack and bake for 16–20 minutes, or until the centers are set and a toothpick comes out mostly clean. The tops may puff slightly.
Rest and release: Let the muffins cool in the tin for 3–5 minutes.
Run a thin knife around the edges if needed, then remove to a cooling rack.
Serve or store: Enjoy warm, or cool completely before storing for later.