Warm a Dutch oven over moderately high heat until hot. Add the beef and brown it, stirring frequently, for about 7 minutes or until its no longer pink and has released its juices. Remove from the heat and spoon the meat into a sieve set over a bowl. Allow all the fat to drain from the meat for at least 10 minutes. Add the turkey to the beef. In the same Dutch oven, heat the olive oil over moderately high heat. Add the onions, garlic, and carrots, and saute about 10 minutes or until softened and golden brown. Return the meats to the pan. Stir in the crushed tomatoes, thyme, salt, and pepper, and bring the mixture to a boil. Cover and simmer, stirring occasionally, for about 25 minutes or until a rich stew has formed. Preheat the oven to 400-F. Transfer the meat mixture to a 9-inch by 13-inch baking dish and smooth out to an even layer. Spread the mashed sweet potatoes over the meat, and smooth the surface with a spatula. (You may want to warm the leftover mashed sweet potatoes with the milk in the microwave briefly, in order to make the vegetable easier to spread in a single layer.) Bake about 15 minutes or until heated through and bubbling around the edges. Serve warm with a parsley garnish. Posted to dailyrecipe@recipe-a-day.com by Recipe-a-Day on Nov 27, 1999, converted by MM_Buster v2.0l.