In a large mixing bowl, toss the acorn squash, potatoes, and onions with 2 tablespoons of the olive oil and a little salt and pepper. Lay them out evenly on a baking sheet or in a large casserole dish and place them in the oven.
After about 30 minutes, coat the garlic cloves in 1/2 tablespoon of the olive oil and a little salt and pepper and scatter over the roasting.
vegetables. Return to the oven.
After 10 minutes more, toss the pear and thyme with the remaining 1/2 tablespoon of olive oil and a little salt and pepper and distribute evenly over the pan of roasting vegetables. Return to the oven for another 15 minutes.
Arrange the hot vegetables on a large platter, drizzle with Balsamic Vinegar, and crumble the goat cheese over the top. Place the entire platter in the oven for 2 or 3 minutes, just to lightly melt the cheese. Sprinkle the hazelnuts over the top and serve immediately.