Acorn Squash Stuffed with Muschrooms and Grain

The cookbook in the Food 52 Cooking Club this month is Diana Henry's From the Oven to the Table.  She does this in mini pumpkins, but I had acorn squash and so that is what I chose to stuff.

2 small of 1 large acorn squash
1 oz. dreid porcini mushrooms
1 lb fresh cremini mushrooms
10 scallions
2 cups cooked grains (I used buckwheat groats for their earthy flavor, but farro, barley, or lentils even would work)
1 clove garlic, minced
salt
pepper
olive oil
grated gruyere (optional)
cream (optional)

Preheat the oven to 400 degrees.  Cut the acorn squash in half, seed, rub with olive oil, and salt and pepper.  Place on baking sheet cut side down and roast until tender, about 30 minutes.
Put the dried mushrooms in a bowl with enough boiling water to cover them, and let sit.
Slice cremini mushrooms and toss with olice oil, salt and pepper, and roast along side the acorn squash for 30 minutes.  This is a good use of an already hot oven, and the mushroom flavor is unbelievable.  In yet another pan roast the scallions for about 10 minutes after tossing in olive oil, salt and pepper.
Chop the scallions, chop the rehydrated dried mushrooms, and add them plus the mushroom liquid, the garlic, and the roasted mushrooms to the grain and stir, flavoring to taste.
Stuff the squash, sprinkle with cheese and/or cream and put back in the oven to reheat, about 20 minutes.