Spinach, Cheese & Caramelized Red Onion Frittata
- Position a rack in the center of the oven and heat the oven to 450°F. Heat 2 Tbs. oil in a large (12-inch), oven-proof, nonstick skillet over medium-high heat. Add the onion, sprinkle with 1/2 tsp. salt, and cook, stirring until it starts to color and soften, about 2 minutes. Reduce the heat to medium, add the jalapeño, and continue cooking until the onion softens almost completely, about 5 minutes. Add the spinach, sprinkle with 1/2 tsp. salt, increase the heat to high, and cook, tossing, until the spinach just wilts, about 2 minutes. Remove from the heat and let cool for a couple of minutes.
- In a large bowl, whisk the eggs with the Parmigiano-Reggiano cheese, sun-dried tomatoes, basil, 1 tsp. pepper, and 1/4 tsp. salt. Add the vegetables from the skillet to the egg mixture and stir to combine.
- Wipe the skillet with a paper towel and heat the remaining 2 Tbs. oil in it over medium heat. Add the egg mixture and cook, running a spatula along the bottom of the pan to prevent sticking, until the eggs begin to set around the edges, about 3 minutes. Transfer the skillet to the oven and bake until the eggs puff and are firm to the touch and browned on top, about 12 minutes. Let cool for a couple minutes, then slide onto a cutting board, cut into wedges, and serve.