Step 1

Heat oil in a 12-inch cast iron pan over medium-high heat. Add ground beef, onion, and mushrooms. Break ground beef apart as it cooks and cook until beef is browned and onion and mushrooms are soft, about 5 minutes.

Step 2

Add garlic, salt, pepper, and thyme and cook 1 minute.

Step 3

Stir flour into mixture and cook 1 minute.

Step 4

Stir in tomatoes, condensed French onion soup, beef broth, parsley, vinegar, and garlic powder.

Step 5

Simmer for 10 minutes, stirring occasionally.

Step 6

Meanwhile, peel potatoes and cut into 1 1/2-inch chunks. Place in a pot and cover with water. Add salt to the water ( a few teaspoons) and bring to a boil. Simmer until potatoes are soft.

Step 7

Drain potatoes. add butter, milk, and cheese. Mash with a potato masher until smooth. Season to taste with salt and pepper.

Step 8

Spread potatoes on top of beef mixture. Transfer pan to oven and broil for about 3 to 5 minutes.