Frittata with Potatoes, Red Peppers, and Spinach

Ingredients

• 8 large eggs
• 1/4 cup milk
• Salt and freshly ground black pepper
• 2 tablespoons olive oil
• 1 medium onion, diced
• 1 large potato, peeled and thinly sliced
• 1 red bell pepper, cored, seeded, and sliced into thin strips
• 2 cups fresh spinach leaves
• 1/2 cup grated Parmesan cheese
• Optional: fresh herbs like parsley or basil for garnish