Italian Stacked Omelet - Ohio Eggs

Ingredients

• Vegetable oil
• 1/2 cup finely diced onion
• 3 cloves garlic, minced
• Salt and pepper, to taste
• 12 Ohio eggs
• 1/2 lb ground North Country Charcuterie Hot Italian Sausage
• 1 cup shredded Mozzarella cheese
• 1 cup shredded Parmesan cheese
• 1/2 cup marinara sauce, plus more for serving