Roasted Squash with Shallots, Grapes, and Sage

acorn squashes (about 1 1/2 pounds each)

plus 1 teaspoon extra-virgin olive oil

Coarse salt and freshly ground pepper

mixed black and red grapes (about 3 cups)

large shallot, thinly sliced (about 1 cup)

packed small fresh sage leaves

cooked spelt, wheat berries, barley, or other whole grain