This frittata is a crustless baked egg dish made with Yukon gold potatoes, onions, fresh basil, and Gruyère cheese. Ina’s version is simple but packed with flavor. It’s baked in the oven for an easy, hands-off method that delivers consistent results and a golden, puffed finish.
Set your oven to 350°F (175°C). Prepare a 10–12 inch ovenproof skillet or pie dish by greasing it with butter or nonstick spray.
Heat the olive oil in a large skillet over medium heat. Add the diced potatoes and cook for 10–12 minutes, stirring occasionally, until tender and lightly browned. Add the onions and sauté for another 5 minutes until soft and golden. Remove from heat and let cool slightly.
In a large bowl, beat the eggs with salt and pepper until combined. Stir in the basil and Gruyère cheese.
Add the slightly cooled potato-onion mixture to the egg mixture and stir well.
Melt the butter in your prepared skillet or dish. Pour in the egg and potato mixture. Bake for 25–30 minutes, or until the center is just set and the top is puffed and golden.
Allow the frittata to rest for 5–10 minutes before slicing. Garnish with extra basil or cheese if desired.