Grilled Vegetable Muffulettas

Name: Grilled Vegetable Muffulettas
Ingredients: 1/4 cup plus 2 tablespoons walnuts; 1/2 cup oil-packed sun-dried tomatoes, drained; 1/4 cup freshly grated Parmesan cheese; 1/2 cup (tightly packed) basil leaves; 1 tablespoon minced garlic; 2 tablespoons extra-virgin olive oil, plus more for brushing; Salt and freshly ground pepper; 2 medium red bell peppers; 2 medium zucchini, sliced lengthwise 1/4 inch thick; 1 small eggplant, sliced crosswise 1/4 inch thick; 1 large baguette, halved lengthwise; 20 small spinach leaves, washed and dried; 1/2 pound sliced Provolone cheese