Spinach and Feta Skillet Frittata

Steps

1. Heat the oven to 375°F (190°C) with a rack in the middle.
   375°F
2. Whisk (how to whisk)

   Whisk Beat ingredients with a whisk to mix them smoothly or to add air. 1. Use a bowl big enough to whisk without splashing; set it on a damp towel to stop it spinning.2. Hold the whisk loosely and move it in quick circles or side to side, touching the bottom.3. For lumpy mixtures, add liquid a little at a time and whisk after each.4. For sauces on the stove, keep the whisk moving across the whole bottom of the pan. Done when: The mixture is even with no lumps or streaks of egg. How to whisk: mistakes to avoid

   the eggs, milk, salt and pepper in a bowl until completely smooth.
3. Heat the oil in a 10-inch oven-safe skillet over medium heat. Add the onion and cook until soft.
   ⏱ Soften onion: 4 min
4. Add the garlic and stir for 30 seconds until it smells fragrant.
   ⏱ Garlic: 30 sec
5. Add the spinach a handful at a time, stirring until it all wilts.
   ⏱ Wilt spinach: 2 min
6. Spread the vegetables evenly over the bottom of the pan and pour in the eggs.
7. Scatter the feta and tomatoes, if using, over the top.
8. Cook on the stove without stirring until the edges begin to set.
   ⏱ Set edges: 3 min
9. Move the skillet to the oven and bake until the center is set and puffed and no liquid egg runs when you cut a small slit in the middle. The center should read 160°F (71°C).
   375°F⏱ Bake: 12 min
10. Use an oven mitt to take out the skillet (the handle is hot). Let the frittata

    rest (how to rest)

    Rest Leave cooked meat, baked goods or dough alone for a while before you cut, slice or shape it. 1. Move meat to a board or plate as soon as it is done (a few degrees shy of target for big roasts; it keeps rising).2. Tent it loosely with foil if the kitchen is cool.3. Rest steaks and chops 5 minutes, roasts 15 to 20, a turkey 30.4. For dough, cover it so it doesn't dry out while it relaxes. Done when: Meat juices stay in when you slice; dough rolls out without springing back. Safety: Rest at room temperature for under an hour, then refrigerate leftovers within 2 hours of cooking.How to rest meat and dough: mistakes to avoid

    , then loosen the edges with a spatula and cut into wedges.
    ⏱ Rest: 5 min

Tap an underlined word for how to do it, or see all techniques.

Tips

• Pull it from the oven as soon as the center is set. Overbaked frittata turns spongy.
• Cast iron should be well seasoned, or rub it with an extra teaspoon of oil so the eggs release.

Storage

Refrigerate wedges up to 4 days. Eat cold, or reheat to 165°F (74°C).

How long leftovers keep, and freezing and reheating: leftovers and storage. In season: spinach (March to May and September to November).