Easy Chunky Tomato Soup

2 tablespoons vegetable oil
1 medium onion, chopped
2 tablespoons all-purpose flour
1/2 cup milk
1 jar (26-28 oz) tomato paste sauce
1 can (14.5 oz) diced tomatoes with basil, garlic, and oregano; undrained
1 can (14 oz) chicken broth
3/4 cup finely shredded Cheddar-American cheese blend

1) In 4 qt. saucepan, heat oil over medium heat. Add onion, cook and stir until softened. Add flour; cook and stir until moistened. Gradually add milk cooking and stirring about 2 minutes or until smooth and bubbly.
2)Stir in pasta sauce, tomatoes, and broth. Cover; cook over medium heat about 15 minutes, stirring frequently, just until mixture boils. Top each serving with 3 tablespoons cheese.