Preheat oven to 400°F. Toss squash, onion, and Brussels sprouts in 2 tablespoons olive oil. Spread on a baking sheet and sprinkle with salt and pepper. Roast for approximately 25-30 minutes or until squash is golden with crisp edges. Stir after 15 minutes.
Toss bread cubes with remaining 2 tablespoons of olive oil. Spread on a second baking sheet and add to oven. Bake 10-15 minutes or until edges are golden and crispy. Stir halfway through baking time.
For the Dressing, melt butter over medium-high heat and continue to cook, stirring constantly, until butter turns a nut-brown color. Butter should have a nutty fragrance.
Set aside to cool for about 5 minutes. Add chopped fresh herbs, balsamic, and lemon juice. Stir to combine and set aside.
Fry chopped bacon until crispy, drain off fat and set aside.
Once vegetables are finished roasting, toss vegetables with the bread cubes, bacon, walnuts, and cranberries in a large bowl and toss with balsamic dressing. Let sit 10 minutes to allow dressing to soak in. Stir in grated gruyère.
Divide salad greens between bowls and top with panzanella and extra grated gruyere if desired.