For the Acorn Squash: Slice squash in half. Scoop out seeds, leaving a hollow cavity in the middle of each half. Rub with oil, salt and pepper. Place cut side down on a baking sheet; roast at 400°F 30 minutes. 

For the Filling: Cook rice according to package directions. 

In a nonstick skillet or Dutch oven over medium heat, cook lamb, with a dash of salt and pepper, until done and browned through; set aside. Wipe out pan. Add oil or butter; add onion and sauté over medium heat until it begins to soften. Add celery, garlic, sage, thyme and a pinch of salt and pepper; cook, stirring, until celery is crisp tender. Add apples, cranberries and cooked rice; stir to combine. Add lamb last. Season as desired. 

Spoon mixture into hollowed out squash halves, filling completely. Place squash back on the baking sheet, right side up; sprinkle with parmesan (if using). Bake for 5 to 7 minutes, until the cheese is melted. 

Serve as a main dish as is, or slice each in half to be used as a side. Store leftovers, tightly covered, in the fridge for up to 5 days.