Add baby bella and shitake mushrooms to a food processor and either pulse or shred, until minced
Transfer mushrooms to a large skillet or dutch oven
Add celery chunks, carrot chunks, garlic cloves, and onion pieces to the food processor and pulse/shred
Add the celery/carrot/garlic/onion mixture to the mushrooms in the pan
Add 1 teaspoon of salt and ½ teaspoon of pepper to the vegetables
Turn the burner on medium high heat and sautee vegetables for 25-30 minutes, stirring often, until vegetables cook down and most of the liquid evaporates
Puree diced fire roasted tomatoes in the food processor until smooth
Add the pureed tomatoes to the vegetables along with the basil, oregano, nutritional yeast, and sugar
Taste and add any seasonings if necessary (if it tastes too acidic, add a little more sugar as necessary)
Heat until hot throughout, then serve
Serve over spaghetti and topped with parmesan cheese, if desired