Prep time: 20 min
Cook time: 30 min
2 tablespoons olive oil
1 large leek (white part only), chopped
1 teaspoon salt, divided, or as needed
1 jalapeño pepper, seeded and diced
1½ cups (½-inch) sliced zucchini
1½ cups (½-inch) pieces asparagus
1 cup baby spinach
1½ cups sliced cooked potatoes
12 large eggs
1 pinch cayenne pepper
½ teaspoon freshly ground black pepper
4 ounces crumbled goat-milk feta cheese, divided
Preheat oven to 350 degrees F (175 degrees C).
Heat oil in heavy 10-inch skillet over medium heat. Cook leek with a pinch of salt, stirring occasionally, until leeks soften and start to turn translucent, 5 to 6 minutes. Add jalapeño and zucchini; season with pinch of salt. Cook until zucchini start to get tender and pale green, about 5 minutes. Add asparagus and cook until bright green, about 1 minute. Add spinach and another pinch of salt, cooking until wilted, 1 minute. Stir in cooked potatoes and heat through, about 5 minutes.
Crack 12 large eggs into a bowl. Add cayenne, salt, and pepper. Whisk for at least 30 seconds. Pour eggs over vegetables in skillet over medium heat. Add 3 ounces of crumbled goat cheese; stir lightly until evenly distributed. Top with remaining cheese. Remove from heat.
Bake in preheated oven until eggs are set, 12 to 15 minutes. When nearly set, turn on broiler. Broil frittata until top browns, 1 to 2 minutes. Cool slightly; serve warm.