Step 1

POSITION rack in centre of oven and preheat to 375F. Line a 12-cup muffin pan with paper liners.

Step 2

STREUSEL : Mix sugar, flour and salt in a small bowl. Add butter and blend with fingertips until crumbly. Set aside.

Step 3

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.

Step 4

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.