- 2 tbsp unsalted butter
- 1 large onion, sliced
- ¾ tsp kosher salt
- Freshly ground black pepper
- 8 large eggs
- ¼ cup milk
- 1 cup diced ham
- 1 tbsp chopped fresh herbs, like parsley, thyme or dill
- 1 cup grated Swiss or cheddar cheese, or any cheese you prefer
Position rack in oven about 8 inches from the broiler and preheat oven to broil. Melt the butter in a medium non-stick skillet or cast-iron skillet. Add the onions and season with ½ tsp salt and some pepper. Cook, stirring occasionally, until the onions get very soft, about 15 minutes. Meanwhile, whisk the eggs and milk in a medium bowl with the remaining ¼ tsp salt and some pepper until smooth. Transfer onions to a bowl to cool. Reserve the skillet.
Stir the onions, ham, herbs and cheese into the eggs.
Pour the frittata mixture into the skillet over medium heat and stir to make sure the fillings are evenly arranged. Cook, stirring gently a couple of times in the first minutes of cooking. Then let the mixture cook undisturbed until the bottom sets, about 5 minutes. Transfer the skillet to the oven and broil until the eggs are just set and brown, about 5 minutes. Take care not to overcook or the eggs will be dry. Remove from the oven, cover, and set aside for 5 minutes.
Invert the frittata onto a large platter or plate. Cut into wedges and sever warm or at room temperature.