• Preheat oven to 375 degrees.
• Place sweet potatoes in a large pot and cover with cold water. Bring to a boil. Boil until potatoes are fork tender, about 10 minutes depending on how thick you cut the potatoes.
• Drain the water from the potatoes, turn off burner, and return to pot. Then, add the allowed butter, salt, pepper, garlic powder, and 1/4 C of the non-dairy milk. Mash with a potato masher or use an immersion blender or food processor for a creamier texture. Add the rest of the non-dairy milk as needed then stir in the egg yolk until well combined. Set aside.
• In a large, heavy bottomed pot or dutch oven, melt 2 Tbsp coconut oil over medium heat. Add the carrots, onion, and celery, and cook, stirring 5 minutes. Add the ground meat and garlic. Cook, stirring often and breaking up meat, until browned, 7 - 10 minutes. Drain meat of fat. Add the peas, tomato paste, salt, pepper, thyme, oregano, and Worcestershire sauce and mix well.
• Spoon the meat mixture evenly into a casserole dish or a 9x12 in glass baking dish. Carefully spread the mashed sweet potatoes over the top of the meat mixture. Bake for 30 minutes, letting the top slightly brown.* Cut into slices and serve.

*For more of a golden-brown topping on the sweet potatoes move the oven rack up one slot from the middle.