In 10-inch skillet, heat 2 tablespoons olive oil over medium heat; add 1 yellow onion, diced. Season with salt and pepper; cook about 5 minutes, stirring occasionally, until onion starts to brown. Add 1 1/2 lb ground beef; sprinkle with more salt and pepper. Cook 5 to 6 minutes, stirring frequently, until browned. Stir in 1 jar (25.5 oz) Muir Glen™ classic marinara pasta sauce; heat until warmed.