Easy Mother's Day Sunday Brunch: Frittata with Spinach and Cheese Recipe

Ingredients (7)

• 2 pounds spinach, tough stems removed and rinsed well
• 2 tablespoons extra-virgin olive oil
• 1 onion, finely chopped
• 8 large eggs
• 1/4 cup fresh or aged sheep or goat cheese (cheddar will also do just fine)
• 1/4 cup freshly grated Parmigiano-Reggiano
• Salt and freshly ground pepper