Heat a large skillet over medium-high heat. Add the ground meat, onion, carrots, salt, and pepper. Cook for 10-15 minutes, breaking up the meat into small pieces until the meat has fully cooked through. Drain off an excess grease from the meat mixture. Add the garlic and cook for another minute.
Add the meat back to the skillet and sprinkle the gluten-free flour over the meat. Cook over medium to medium-high heat for a minute or so, stirring constantly. Stir in the tomato paste, stock, Worcestershire sauce, oregano, thyme, and rosemary. Bring to a simmer and continue to simmer gently for 10 minutes.
Stir in the corn and pea and continue to cook for another 2-3 minutes until heated through.
Pour the meat filling into the prepared pan. Spread the mashed potatoes evenly over the meat filling all the way to the edges of the pan. Bake for 30 minutes.
Top with the remaining 1 cup cheddar cheese and bake for another 10-15 minutes until golden and bubbly. Let sit for 10 minutes before serving. Enjoy!