Place the four quarts water in a large stock pot over high heat.
When the water boils, add the whole spaghetti squash (watch out that the hot water doesn’t overflow the stock pot). Cook for 40 minutes.
Remove the squash from the water, place it whole on a plate or cutting board, and let the squash cool enough to handle.
Cut the squash open and scoop out the seeds. Scoop the flesh of the squash away from the tough skin into a large mixing bowl and discard the skin.
While the squash is cooking, place the olive oil in a large skillet over medium high heat.
Add the garlic and onions and cook for about 5 minutes.
Add the mushrooms and cook for about 5 minutes.
Add the tomatoes, basil, oregano, sage, and fennel.
Simmer for about 30 minutes. Stir frequently.
Remove from the heat and let cool.
Preheat the oven to 325°F.
Place the tomato sauce, milk and parmesan cheese in the mixing bowl with the spaghetti squash. Fold together gently.
Place the mixture in a 9 inch Pyrex dish.
Cover with foil and bake for 25 minutes.
Uncover and top with the provolone cheese.
Bake for 10 minutes.
Serve.