In a large stock pot or dutch oven, steam butternut squash and chard in an inch or two of water, until squash is fork tender. Add squash and chard to a blender or food processor, and process until smooth (you may need to add a little bit of water to help it along).

In the same pot that was used for steaming, heat olive oil over medium heat. Add the onion and garlic, and cook until translucent. At this point, add the pureed vegetables back in, as well as the mushrooms, tomatoes, and dried oregano.

Allow to simmer for 20-30 minutes. Add salt and pepper, to taste, then chop fresh basil and stir in.

Serve with your favorite noodles, zucchini noodles, meatballs, or anywhere else that you'd use a classic marinara sauce.

This sauce freezes beautifully, so feel free to make a larger batch to store for later. Once cooled, pour about 2 cups in a quart size freezer bag, and store flat in the freezer until frozen.