1. Preheat oven to 350 degrees. Line a muffin tin with muffin papers (12).
2. In a small bowl, combine topping ingredients: sugar, brown sugar and cinnamon. Set aside for now.
3. In a large bowl, combine the wet ingredients: sourdough discard/starter, butter, egg and vanilla. Mix well (I used a hand mixer here).
4. Add in dry ingredients: flour, sugar, brown sugar, baking soda, salt, cinnamon and nutmeg. Mix until combined.
5. Fill each muffin cup about two thirds full, while being careful not to fill them too ful.
6. Sprinkle the topping on each muffin.
7. Bake for 20 minutes or until a toothpick inserted into the center of a muffin comes out clean.
8. Remove from oven and allow to cool before eating.