Preheat the oven to 350 degrees. Line two muffin tins with cupcake liners or spray them well with baking spray. Set aside.
In a large bowl combine the butter, sugar, molasses, eggs, and pumpkin. Mix well until combined.
Add in the sourdough starter discard and vanilla and mix until combined.
In a medium bowl combine the flour, salt, pumpkin pie spice, baking powder and baking soda.
Add the flour mixture to the pumpkin mixture and mix until evenly combined.
Fold in the cranberries and walnuts.
Fill each muffin cup 3/4 of the way full.
Bake for 22-25 minutes or until a toothpick inserted into the center comes out clean.
Remove from oven and cool completely on a wire rack.