How to Make It
Make cupcakes: Preheat oven to 375°F. Line a 6-cup muffin tin with paper liners. Grate apple using a box grater (large or medium grates), making sure to stop before you hit core. Squeeze grated apple in a fine-mesh sieve over sink to remove excess moisture.
In a large bowl, mix flour, baking powder, cinnamon, salt and sugar. In a small bowl, whisk yolk, milk, oil and vanilla. Stir into dry ingredients until just moistened. Stir in grated apple.
Fill each muffin cup two-thirds full. Bake until cupcakes are golden and a toothpick inserted into center of a cupcake comes out clean, 20 to 22 minutes. Let cupcakes cool in pan for 5 minutes, invert onto wire rack and turn them right side up to cool.
Make glaze: Whisk confectioners' sugar and lemon juice in a small bowl. Drizzle glaze over cupcakes and serve.