Crispy Chicken and Scallion Waffle Sandwich

Name: Crispy Chicken and Scallion Waffle Sandwich
Ingredients: 2/3 cup buttermilk; 1 1/2 teaspoons hot sauce; 1 1/2 teaspoons kosher salt; 1/2 teaspoon granulated garlic; 1/2 teaspoon granulated onion; 2 pounds boneless chicken tenders; Vegetable oil, for frying; 2 cups unbleached all-purpose flour; 2 teaspoons smoked paprika; Salt and freshly cracked black pepper; 3 cups panko breadcrumbs; 3 tablespoons ancho chile powder; 3 large eggs; 8 tablespoons (1 stick) salted butter, softened; 3 tablespoons maple syrup; 3 teaspoons hot sauce; 1/4 teaspoon cayenne pepper; 2 tablespoons vegetable oil; 3/4 teaspoon vanilla extract; 2 large eggs; 1 1/4 cups buttermilk; 1/2 cup seltzer; 2 tablespoons sugar; 1/2 teaspoon table salt; 1/2 teaspoon baking soda; 1 cup chopped scallions; Nonstick cooking spray; 4 tomatillos, cleaned and thinly sliced, for serving