Preheat oven to 400℉. Bake the sweet potatoes until fork tender, 45 to 60 minutes. Alternatively, you can steam peeled and diced sweet potatoes until tender.
In a medium 10-inch oven safe skillet over medium-high heat, saute the ground beef and onion until the beef is no longer pink.
Stir in the garlic, tomato paste, worcestershire sauce, rosemary, and thyme. Cook another 1-2 minutes. Stir in the salt, pepper, vegetables, and broth. Bring to a simmer and then turn off the heat.
To make the topping: Place the peeled and baked/steamed sweet potato, butter, and salt in a food processor (or stand mixer) and process until smooth.
Top the meat filling with the sweet potato mash. If you’re not using an oven-safe skillet, transfer the meat filling to a casserole dish or 9×9 inch baking dish and top the meat filling with the sweet potato mash.
Bake for 10 minutes. Remove from the oven and sprinkle with some flakey sea salt and chopped fresh parsley and serve.