1.Preheat oven to 350°F.
2.Heat 2 teaspoons oil in a 10" ovenproof nonstick skillet over medium heat. Add leeks, 1⁄4 teaspoon salt, and a 1⁄4 teaspoon pepper. Cook 5 minutes. Stir in grape tomatoes and capers. Cover and cook 3 minutes. Transfer to a small bowl.
3.In a medium bowl, quickly beat egg whites with herbes de Provence, thyme, and remaining salt and pepper. Whisk in egg yolks. Whisk until mixture is fluffy.
4.Brush skillet with remaining olive oil. Add eggs, cooked tomato mixture, and goat cheese. Cook over medium heat 4 minutes. Transfer to oven; bake 15–20 minutes or until eggs are set. To check, cut a small slit in center of frittata.