This is frittata for a crowd, or for stowing away so that you’re armed with delicious, ready-to-eat leftovers all week long. Let seasonal produce, your crisper drawer, and/or whatever odds and ends of leftovers you’ve got be your guide as you decide on fillings, supporting them with alliums and complementary herbs and cheese. But don’t plan for the fillings themselves to finish cooking inside the frittata—an undercooked potato will still be undercooked in the finished dish, and the same goes for a sliver of onion—so make sure they taste as you want them to before stirring them into the eggs. Additionally, watery vegetables that “leak” as they cook, like summer squash or fresh tomatoes, should first be cooked or salted and drained so that they dry out, else they’ll waterlog the finished dish—and cooked leafy greens (spinach, kale, Swiss chard) should be squeezed dry.
1 big bunch blanched asparagus + 2 leeks + 1 tablespoon chopped tarragon + 6 ounces crumbled goat cheese
1 cup drained, chopped kimchi + 5 ounces wilted spinach + 1 bunch scallions + 6 ounces cubed cheddar cheese
1 large or 2 small roasted, peeled, and diced sweet potatoes + 1 large onion, caramelized + ½ cup chopped cilantro leaves and stems + 5 ounces cubed feta
- Preheat the oven to 300°F. Prepare your sheet pan by brushing it—especially the sides—thoroughly with olive oil, then line it with parchment paper so that there's overhang on the longest edges. Brush the parchment with olive oil.
- Cook your alliums: Warm a splash of olive oil in a skillet, then add the alliums with a pinch of salt. At the very least, cook them over medium heat until the raw bite is cooked off. If you wish to caramelize them, cook on medium-low heat, stirring every now and then, until reduced, sticky, browned, and sweet. Timing will vary depending on what type of allium you use, so you must taste as you go! Cool for at least 10 minutes.
- In a large mixing bowl, whisk together the eggs, cream, olive oil, salt, and pepper. Fold in all the fillings except for ricotta cheese, if using. Scrape the mixture into the prepared sheet pan using a rubber spatula, and gently nudge around the fillings so that they're evenly distributed. Dollop the ricotta over the surface if you're using it.
- Carefully transfer the pan to the oven and bake for 25 to 30 minutes, rotating once halfway, until the eggs are set and there aren't any puddles of uncooked egg on the surface. If your oven isn't level, rotate the pan every 8 minutes or so, which will help to get you an even frittata.
- Cool for at least 15 minutes before serving. The best way to slice is to run a sharp knife around the un-parchment-ed edges, then flip the pan over onto a big cutting board or other clean work surface. Peel off the parchment. Don't bother trying to flip it back upright, as it'll most definitely tear in half. Use a chef's knife to cut it into rectangles or squares, turning them upright to serve. This is good warm, at room temperature, or cold. Kept in an airtight container in the refrigerator, the frittata will keep for 3 or 4 days.
Lukas Volger is the author of the forthcoming cookbook Start Simple and three other cookbooks, and the editorial director of the queer food journal Jarry. He lives in Brooklyn.