A simple, fluffy frittata with cubed ham, sautéed onion, and melty Swiss cheese baked into tender eggs. Ready in 25 minutes and easy to customize with whatever cheese or vegetables you have on hand.
In a bowl, whisk together eggs, heavy cream, salt, and a few pinches of black pepper until well combined and slightly frothy. Pat ham dry with paper towels if needed.
Melt butter in a 10-inch oven-safe nonstick skillet over medium heat. Add onion and cook until softened, 3 to 4 minutes.
Add ham and cook 1 to 2 minutes to warm through.
Pour the egg mixture into the skillet and gently stir once or twice to distribute ingredients evenly. Sprinkle cheese over the top.
Cook undisturbed for 2 to 3 minutes, until edges begin to set.
Transfer skillet to the oven and bake for 12 to 15 minutes, until the center is set and slightly puffed. Begin checking after 10 minutes.
Remove from oven and let rest 5 minutes. Run a spatula around the edges, then slice and serve directly from the pan, or transfer to a serving plate. Garnish with sliced green onion or chives and serve immediately.
Notes
Cheese options: Swiss is the recipe's first choice, but cheddar, Gruyere, smoked Gruyere, pepper jack, or colby jack all melt beautifully. Stick with a melty cheese for the best texture.
Ham source: Leftover holiday ham, store-bought cubed ham, or a half-inch slab of ham from the deli counter (cubed at home) all work. Ask the deli for a pound sliced thick.
Vegetable add-ins: Keep total fillings around 3 cups. Sautéed bell pepper, mushrooms, wilted spinach, or cooked potato all work. Cook watery vegetables first.
Protein swap: Cooked, crumbled breakfast sausage or chopped cooked bacon can stand in for the ham.
Half-and-half can be substituted for the heavy cream. Whole milk works in a pinch but the texture will be slightly less rich.
Pat the ham dry before adding to the skillet. Excess moisture leads to watery eggs.
Don't overbake. Pull from the oven when the center just sets and puffs slightly. Residual heat finishes the cook during the 5-minute rest.
Storage: Refrigerate in an airtight container for up to 3 days. Reheat at 50% power in the microwave for 1 to 2 minutes.
Freezing: Wrap tightly in waxed paper, then plastic wrap and foil. Freeze up to 2 months. Thaw overnight in the fridge.