Butternut Squash Gratin - With greens

3 1/2 pounds butternut squash (about 2 medium), peeled, seeded, cut into 3/4- to 1-inch cubes (8 cups) 2 tablespoons olive oil Coarse kosher salt 4[...]

3 (12 ounce) boxes frozen squash, thawed & drained (I use Birds Eye) or 3 lbs butternut squash, peeled,seeded & cut in cubes 6 tablespoons brown sugar 2[...]