Ingredients:
- Cupcakes:
- ½ cup granulated sugar
- ½ cup packed brown sugar
- 6 tablespoons butter, softened
- 3 large eggs
- 1 teaspoon vanilla extract
- 8 ounces cake flour (about 2 cups)
- ½ teaspoon baking soda
- ¼ teaspoon salt
- ¼ teaspoon ground cinnamon
- ½ cup buttermilk
- ⅓ cup plus 2 tablespoons walnuts, toasted, chopped, and divided
- Frosting:
- ½ teaspoon cream of tartar
- 3 large egg whites
- ¾ cup maple sugar or granulated sugar
- ¼ cup water
- Dash of salt