📖 Instructions

1. **Preheat Your Oven:** First things first, get that oven ready! Adjust an oven rack to the middle position and preheat your oven to 375°F (190°C). This ensures a nice, even bake for your frittata.
2. **Prepare the Vegetables:** Take out your cutting board and a sharp knife. Wash and dice your bell pepper into small, roughly 1/2-inch pieces. Halve the cherry tomatoes. Chop the zucchini into similar 1/2-inch chunks. If using spinach, give it a rough chop. You want all your veggies to be bite-sized and cook evenly.
3. **Sauté the Harder Veggies:** Place a 10-inch oven-safe non-stick skillet or a well-seasoned cast iron pan over medium heat. Add 1 tablespoon of olive oil. Once the oil shimmers, add the diced bell pepper and zucchini. Sauté for about 5-7 minutes, stirring occasionally, until they start to soften and get a little color. You're looking for tender-crisp, not mushy.
4. **Add Softer Veggies & Aromatics:** Now, toss in the halved cherry tomatoes and minced garlic. If using spinach, add it now too. Continue to cook for another 2-3 minutes, just until the tomatoes begin to soften slightly and the spinach wilts down. The garlic should smell fragrant but not browned or burnt. Season this veggie mixture with 1/4 teaspoon salt and 1/8 teaspoon black pepper. Remove the pan from the heat and spread the veggies evenly across the bottom.
5. **Whisk the Eggs:** In a large mixing bowl, crack your 6 large eggs. Add the milk, remaining 1/4 teaspoon salt, and 1/8 teaspoon black pepper. Whisk vigorously with a fork or a whisk for about 1 minute until the eggs are well combined, slightly frothy, and a uniform pale yellow color. This helps create a light and airy frittata.
6. **Assemble the Frittata:** Gently pour the whisked egg mixture evenly over the sautéed vegetables in the skillet. Make sure the veggies are submerged. Crumble the feta cheese over the top of the egg mixture. You can give the pan a gentle shake to ensure even distribution.
7. **Initial Stovetop Cook:** Return the skillet to medium-low heat. Cook on the stovetop for about 5-7 minutes without stirring. You'll see the edges of the frittata start to set, and the bottom will become firm. The center will still be liquid and wobbly. This step helps create a nice crust on the bottom and prevents sticking.
8. **Finish in the Oven:** Carefully transfer the skillet to your preheated oven. Bake for 15-20 minutes, or until the frittata is puffed up, golden brown on top, and the center is set (no more jiggle when you gently shake the pan). You can insert a thin knife or toothpick into the center; if it comes out clean, it's done.
9. **Cool and Serve:** Once baked, carefully remove the frittata from the oven. Let it cool in the pan for about 5-10 minutes. This allows it to set completely and makes it easier to slice. Garnish with fresh chopped basil or parsley if you like. Slice into wedges directly in the pan, or carefully slide it onto a cutting board. Serve warm or at room temperature. Enjoy your delicious, easy summer frittata!
10. **Storage Tip:** If you have leftovers, cover the skillet with foil or transfer slices to an airtight container. It keeps beautifully in the fridge for up to 3 days. A quick reheat in the microwave or oven makes for a fantastic next-day meal!