Brown and crumble ground beef. Drain excess grease and set aside. Combine first 8 ingredients in a large saucepan; bring to a boil over medium-high heat. Reduce heat and simmer until potatoes are tender. Stir in beef and 2 cups of milk.
In a small bowl, whisk together flour and remaining 1/2 cup milk until smooth. Gradually whisk into soup.
Bring to a boil; cook 2 minutes or until thick and bubbly, stirring constantly (so mixture does not burn.) Reduce heat; add cheese and stir until completely melted. Garnish with bacon.