Sourdough Maple Walnut Bread

I found this recipe on King Arthur’s website. Here is the link: https://www.kingarthurbaking.com/recipes/sourdough-maple-walnut-bread-recipe The recipe calls for unfed/discard sourdough starter. It also calls for white whole wheat flour. This is not something that I usually keep around and I don’t like buying recipe specific ingredients, but. . .I do love maple flavored anything! This recipe also calls for buttermilk. I……