Gather all ingredients. Dotdash Meredith Food Studios
Mix together whole tomatoes, mushrooms, tomato sauce, tomato paste, water, onions, basil, garlic, sugar, 1 pinch of baking soda, salt, and pepper in a large saucepan. Bring to a boil over high heat while stirring, then reduce heat to a simmer, and cook for at least 4 hours. Dotdash Meredith Food Studios
Stir in remaining pinch of baking soda; sauce will foam. Simmer, stirring occasionally, until thick and almost brown. Make sure to scrape the sides of the pan into the sauce. Dotdash Meredith Food Studios
Stir in Parmesan cheese. Taste sauce: if too tangy or acidic, add another pinch of baking soda and simmer for 30 more minutes. Dotdash Meredith Food Studios
Let sauce cool to room temperature, then cover and refrigerate for 8 hours to overnight. Reheat the next day and serve. Dotdash Meredith Food Studios
Mom's Best Spaghetti Sauce · Dinner Match Lab | Dinner Match Lab