In a large pot add the potatoes and cover with water. Add salt to taste. Boil until tender, about 15 min.

In the mean time, heat a large skillet with 1 Tbsp. of canola oil over medium high heat. Add onions and red pepper, cook until lightly browned about 10 min. Transfer vegetables to a bowl with a slotted spoon. In the same skillet add the last tablespoon of oil and fry the mushrooms over medium-high heat until browned about 10 min. Transfer to the bowl with the other vegetables.

Mash the potatoes with the sour cream, milk and butter. Set aside.

Blend the stock with the flour until smooth and set aside.

Preheat oven to 400 F. In the same skillet cook the ground beef. Add salt and pepper to taste, and thyme. Cook until the beef is browned, about 10 min. Add the ketchup, Worchestershire sauce, the cooked vegetable and the stock/flour mixture. Cook until it comes to a boil and thickens slightly. Spoon the mixture into a 2 quart casserole dish.

Top with the mashed potatoes, followed by the chives and the cheese. Place casserole on a rimmed foil-lined cookie sheet to catch any spills. Bake until the cheese is melted and browned and the casserole is bubbling!