Add the garlic and mushrooms and cook them for about 10-15 minutes, until all the liquid has evaporated and the mushrooms have started to brown. (This is a great time to bring a large pot of water to a boil.)
At this point, add the tomato sauce, oregano, salt, pepper, and red pepper flakes to the mushrooms. Stir, and cook for 10 minutes. (While the sauce is cooking, throw the pasta into the boiling water and cook it for about 10 minutes, or until al dente.)
Scoop some water out of the boiling pasta and use it to thin the bolognese sauce and bring it to a nice consistency (you'll need about ½ cup). Add the drained cooked pasta to the mushroom bolognese. Stir everything well, garnish with fresh parsley, and serve.
As the sauce sits, the spices and other ingredients marry together, giving the sauce an even richer flavor the next day. You can keep it fresh in the fridge for up to 4 days in an airtight container or covered dish.