Build the base: Add browned meat to the crockpot. Add 1 yellow onion, finely diced, 2 carrots, finely diced, 2 celery stalks, finely diced, 5 garlic cloves, minced, 2 cans (28 oz each) crushed San Marzano tomatoes, 3 tablespoons tomato paste, ½ cups whole milk, ½ cups dry red wine (or beef broth), 1 teaspoons dried oregano, 1 teaspoons dried basil, 2 bay leaves, 1 teaspoons salt and black pepper, and 1 tablespoons maple syrup. Stir everything together.