cored, diced and peeled Gala
, (about 2 small apples)
POSITION rack in centre of oven and preheat to 375F. Line a 12-cup muffin pan with paper liners.
STREUSEL: Mix sugar, flour and salt in a small bowl. Add butter and blend with fingertips until crumbly. Set aside.
MUFFINS: Whisk flours, sugar, cinnamon, baking powder, baking soda and salt in a large bowl. Whisk egg in a medium bowl, then whisk in buttermilk, oil and vanilla. Stir into flour mixture, just until combined. Fold in apples. Divide among prepared cups, then sprinkle with streusel.
BAKE until golden and a cake tester inserted in centre of muffin comes out with a few crumbs, 18 to 20 min. Let cool in pan for 5 min. Remove muffins to a rack and let cool completely.