1. Preheat the oven to 400°F. Spray an 11 x 7-inch baking dish with nonstick cooking spray.
2. Peel and roughly chop the garlic and onion. Place the garlic, onion, ground beef, ground pork, tomato sauce, parsley, salt, pepper and pepper flakes in the bowl fitted with the ultrablade knife. Mix at speed 12 for 30 seconds.
3. Remove the ultrablade knife, add the pine nuts and mix well, using a spatula.
4. Cut the tops off the peppers and remove the white part and seeds. Place in the prepared dish and fill each pepper with about 1/2 cup of meat mixture. Place the top on each pepper and bake for 40-45 minutes or until internal temperature reaches 160°F.