Greek Mac and Cheese

Name: Greek Mac and Cheese
Ingredients: 3 slices crustless whole wheat bread, torn into small pieces; 9 tablespoons unsalted butter, melted; kosher salt, to taste; 8 ounces hollow pasta (penne or elbow macaroni); 1⁄4 cup flour; 3 cups milk; 4 cups grated graviera cheese (about 12 oz.-you may sub Romano OR Pecorino cheese ) or 4 cups kefalotyri cheese (about 12 oz.-you may sub Romano OR Pecorino cheese ); 3⁄4 teaspoon ground cinnamon; 1⁄8 teaspoon freshly grated nutmeg; fresh ground black pepper, to taste; 2 tablespoons extra-virgin olive oil; 8 large shallots, finely chopped (or 4 small red onions); 1⁄4 cup chopped red bell pepper (or orange or green); 16 ounces Baby Spinach, roughly chopped; 8 scallions, cut into 1/4-inch thick rounds; 1⁄3 cup roughly chopped fresh dill; 1 3⁄4 cups crumbled feta (about 8 oz.)