8 large eggs
1/2 cup finely grated Parmesan
3 large fresh basil leaves, torn into pieces
3 large fresh sage leaves, minced
1 tsp. minced fresh rosemary
1/4 tsp. kosher salt
1/8 tsp. freshly ground black pepper
3 Tbsp. extra-virgin olive oil
1 cup thinly sliced onion
1 cup diced Fontina cheese
Preheat oven to 400°. Whisk first 7 ingredients in a medium bowl; set aside. Heat oil in a medium ovenproof nonstick skillet over medium-high heat. Add onion; sauté until soft, about 6 minutes. Reduce heat to low. Stir in egg mixture. Spoon diced cheese evenly over.
Cook until frittata begins to set, about 2 minutes. Place in oven; bake until just set, 7-9 minutes. Slide the frittata onto a platter. Cut into wedges; serve hot or at room temperature.