First Step: Prep the Vegetables and Ingredients Dice 1 yellow onion and mince 4 cloves of garlic. Open and measure out 2 cans (28 ounces each) of crushed tomatoes and one 6-ounce can of tomato paste. Gather dried basil, oregano, brown sugar, and optional balsamic vinegar. Have your butter (or olive oil) ready. For best results, use a slow cooker with a ceramic insert of at least 3 quarts for even cooking.

Second Step: Combine Ingredients in the Slow Cooker Place the diced onion and minced garlic directly into the slow cooker. Add the crushed tomatoes and tomato paste. Sprinkle in the dried basil and oregano, then add the brown sugar and balsamic vinegar if using. Drop in the butter chunks or drizzle olive oil and stir gently to combine all ingredients thoroughly.

Third Step: Start the Slow Cooker Cover your slow cooker with the lid. Cook the sauce on high for approximately 4 hours or on low for 8 hours. This timeframe lets the flavors develop gradually and the sauce thicken to the perfect consistency. The slow cooker does the work, creating a richly flavored spaghetti sauce with minimal effort.

Fourth Step: Prepare Optional Meat (If Using) If you want to add meat, brown 1 pound of ground beef and/or Italian sausage separately in a pan. Browning develops deeper flavors and helps prevent the meat from overcooking or becoming tough in the slow cooker. After browning, drain excess fat and stir the cooked meat into the sauce after the cooking cycle finishes.

Fifth Step: Season and Finalize Once the slow cooker time is complete, stir the sauce well. Start seasoning with ½ teaspoon of salt, tasting as you go, and adding up to 1 teaspoon total or to your preference. Adjust seasonings if needed for example, a pinch of red pepper flakes for heat or a splash of olive oil for richer mouthfeel.

Final Step: Serve or Store Enjoy your slow cooker spaghetti sauce immediately over cooked pasta of choice. As a tip, toss noodles with a little olive oil after cooking to prevent sticking. You can also refrigerate leftovers for up to 4 days or freeze in portions (2-3 cups per container or quart-sized freezer bags) for 3-4 months. Thaw overnight in the fridge or warm gently on the stove before serving.