Caramelize the onions by melting 2 tablespoons of olive oil and 2 tablespoons of butter over medium-low heat. Add 2 sliced yellow onions and cook for 20–25 minutes until golden brown.

Add 2 cloves minced garlic and 1 teaspoon fresh thyme to the caramelized onions and cook for another 1-2 minutes.

Push the onions aside and brown 1 pound of ground beef in the skillet for 5-7 minutes.

Stir in 1 tablespoon Worcestershire sauce and 1 tablespoon flour. Gradually add 1 cup beef broth, stirring to combine and simmer for 5 minutes.

Remove from heat and stir in 1 cup shredded cheese until melted.

Broil the split hamburger buns for 1-2 minutes until golden brown.

Assemble the Sloppy Joes by spooning the beef mixture onto the toasted buns and serve immediately.