Preheat oven to 350°F. Brush a 12-cup muffin pan with olive oil to coat wells and rims.
Whisk eggs and milk in a large bowl until smooth and lightly frothy.
Season the egg mixture with salt, pepper, garlic powder, and smoked paprika. Whisk to combine.
Fold in ham, cheddar, bell pepper, spinach, and green onions until evenly distributed.
Divide the batter among muffin cups, filling each about three-quarters full.
Bake 16–19 minutes, until set in the center and lightly golden at the edges.
Cool 5 minutes. Run a thin knife around edges and lift out. Serve warm or cool completely for meal prep.