Vegetable oil cooking spray
1/2 cup all-purpose flour
1/2 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
3 large eggs, beaten, at room temperature
2 cups panko breadcrumbs
Four 1/2-inch-thick eggplant slices (1/2 a medium eggplant)
Four 4-inch diameter portobello mushrooms, stemmed
2 tablespoons extra-virgin olive oil, for drizzling, optional
Four 1/2- to 3/4-inch-thick slices country wheat bread, toasted or grilled
3/4 cup jarred tomato-basil sauce, such as Giada De Laurentiis for Target
8 ounces gruyere cheese, shredded
2 cups arugula