In a large skillet, heat the oil and cook the onion over medium heat until it is soft, about 4 minutes.
Add the apple and garlic and cook, stirring, for two minutes more.
Cool the mixture for a few minutes.
In a large mixing bowl, gently combine the onion, apple and garlic mixture, meats, bread crumbs, 2 tablespoons of the horseradish, mustard, thyme, caraway seeds, pepper and eggs.
Shape the meat into a 9-by-5-inch loaf or just pat into a 9-by-5-inch loaf pan, smoothing the top.
In a small bowl, stir together the applesauce and the remaining horseradish.
Spread over the meatloaf and bake until the loaf is firm and brown, about 1 hour.