In a large, high-sided skillet, heat 2 tablespoons of olive oil over medium-high heat. Sauté 1 cup of chopped onion until it turns translucent, which should take about 5-7 minutes, being careful not to let the onion brown. Reduce the heat to medium-low and add 1 tablespoon of minced garlic, cooking until it becomes fragrant, about 1-2 minutes. Increase the heat to medium, add 2 pounds of ground beef along with 1 1/2 teaspoons of salt and 1 teaspoon of black pepper, and cook until the beef is no longer pink, draining any excess fat as necessary. Stir in 2 jars of spaghetti sauce and 3 teaspoons of Italian seasoning.