Swiss Chard Onion Frittata - Oliver's Markets

Ingredients

• 4 teaspoons olive oil, divided
• 1 cup thinly sliced onion
• 4 cups trimmed and thinly sliced Swiss chard
• 1/2 teaspoon kosher salt, divided
• 1/4 teaspoon freshly ground black pepper
• 2 tablespoons chopped fresh flat-leaf parsley
• 4 tablespoons small fresh basil leaves, divided
• 1 teaspoon minced garlic
• 4 large eggs, lightly beaten
• 1.5 oz. Gruyére cheese, shredded and divided (about 1/3 cup)
• 2 tablespoons grated Parmesan cheese