Preheat your oven to 375 degrees F.
Heat olive oil in a large skillet over medium heat.
Add chopped onion and cook until softened.
Add ground beef to the skillet.
Cook until browned. Drain excess fat.
Stir in all-purpose flour and mix well.
Gradually add beef broth, Worcestershire sauce, salt, and pepper.
Simmer until the mixture thickens.
Stir in mixed vegetables and simmer for 5 minutes.
Spread this mixture evenly in a baking dish.
Spoon mashed potatoes over the meat mixture.
Sprinkle shredded cheddar cheese on top.
Bake in preheated oven for 25 minutes or until cheese is golden.