Combine 1/2 cup dry bread crumbs and 3-4 tbsp tomato sauce and set aside.
Melt 1 tbsp unsalted butter in a small skillet over medium high heat.
Either place 1/2 small onion and 8 mushrooms (chopped fine) in a food processor and pulse until coarsely chopped, or finely dice the onion and mushrooms.
Sauté mushrooms and onions until soft, about 8 -10 minutes on medium high. The mushrooms will let out a fair amount of water so the combination must be cooked until the water is mostly reduced and the mushrooms start to brown.
Once the mushroom/onion mixture has reduced, grate one clove of garlic into mixture, add 1 tbsp thyme and stir to combine. Then add 1/4 cup red wine. Cook until the wine has reduced by half, then remove from heat and set aside and cool to room temperature.
Combine 1 1/2 lb ground pork or mixed veal pork and beef with the cooled mushroom mixture, add 1 egg and the reserved bread crumb mixture. Add kosher salt and freshly ground black pepper and using kneading motion, combine well, but do not over work. The mixture should be well combined but still light.
Turn mixture into loaf pan and, if using, spread topping on the top.
Bake in pre heated oven for 1 hour.