Preheat oven to 400°F.
Place the walnuts on a baking sheet and bake for 2-3 minutes. Watch the nuts closely as they burn easily. Combine the brown sugar and ¼ teaspoon pepper, and a pinch of salt. Remove the nuts to a small bowl and drizzle with melted butter. Sprinkle the nuts with the brown sugar pepper mixture and toss to coat. Set aside.
Toss the squash with 1 tablespoon olive oil. Arrange the squash in a single layer on a jelly roll pan and bake for 20 minutes or until the squash is tender and lightly browned/caramelized on the bottom. Remove from the oven and set aside.
In a medium saucepan, bring the 4 cups of vegetable broth and ½ cup of water to a simmer. Do not boil but keep warm on low heat.
Heat a large skillet over medium heat. Add remaining 1 teaspoon olive oil and add the diced onion. Saute the onion for about 3 minutes or until just tender.
Add the minced garlic and saute for 30 seconds.
Add the uncooked rice and cook for 2 minutes stirring constantly.
Add the wine, stir constantly and cook for 1 minute or until the liquid is nearly absorbed.
Add the broth ½ cup at a time, stirring constantly until each portion of liquid is nearly absorbed before adding the next. This will take 20 minutes total.
Stir in the squash, thyme, lemon zest salt and pepper.
Top with walnuts and serve immediately.