Bundt Pan Spanakopita

Name: Bundt Pan Spanakopita
Ingredients: Four 10-ounce packages frozen chopped spinach, thawed and drained; 3 1/2 sticks (28 tablespoons) unsalted butter; 6 scallions, thinly sliced; 3 cloves garlic, minced; 3 tablespoons all-purpose flour; 1 1/2 cups whole milk; Kosher salt and freshly ground black pepper; 8 ounces feta cheese, crumbled; 1 cup fresh Italian flat-leaf parsley, roughly chopped; 1/2 cup fresh dill fronds, roughly chopped; 6 large eggs, beaten; One 1-pound package phyllo dough sheets, thawed if frozen