Preheat oven to 400 degrees.

In a large pan or cast iron skillet, over medium-high heat, add olive oil and let heat for 1-2 minutes. Add chopped onion and a pinch of salt and cook until tender, about 3 minutes. Next, add minced garlic and cook for 2 minutes, stirring so garlic doesn't burn.

Add ground beef to skillet and break up with spoon and cook until completely browned. Remove any excess oil from pan. Return pan to medium heat and add tomato paste and corn starch (or flour). Stir until combined, about 1 minute.

Next, add Worcestershire sauce, beef broth, thyme, salt and pepper, stir into beef mixture and let simmer for about 10 minutes.

Stir in the frozen peas and carrots, and cook for additional 3 minutes. Turn off heat and let sit until ready to top with potatoes.

Cut baby potatoes to ensure all pieces are around the same size, then add to a medium pot and bring to a boil. Cook potatoes until fork tender.

Drain potatoes and return to warm pot.

Add butter and mash potatoes with a masher. Add half and half and mash until creamy. Add 1 cup cheddar cheese and stir into potatoes.

Top beef and veggie mixture with mashed potatoes and spread over top. Add additional cheddar cheese on top of potatoes.

Place pan on a baking sheet (to catch any gravy that spills over.)

Bake in oven for 25-30 minutes.

Remove from oven and let cool 10 minutes before serving.