Greek Yogurt Apple Cinnamon Muffins

For the streusel:
Combine flour, oats, cinnamon and brown sugar in a medium bowl. Cut in the butter until crumbs form. Chill.

For the muffins:

Preheat oven to 425°F. Line a 12-cup muffin tin with paper liners.

Mix all dry ingredients in a large bowl (flours, cornstarch, baking powder salt, cinnamon, apple pie spice).

Whisk together all wet ingredients in a large measuring jug (egg, yogurt, oil, maple syrup, vanilla extract, brown sugar).

Fold the wet into the dry ingredients just until combined. Do not overmix (a few lumps are fine, but there shouldn’t be any obvious flecks of dry flour). The batter will be fairly thick. Fold in apple chunks.

Evenly divide the batter between the prepared muffin cups (this is really easy and mess free with an ice cream scoop). Sprinkle with the chilled streusel.

Reduce oven temperature to 400°F. Bake muffins for 5 minutes. Turn oven temperature down to 350°F and finish baking the muffins for 15–18 minutes or until a toothpick inserted into the middle comes out clean. Cool on a wire rack for 5 minutes before removing from the muffin pan and cooling on the rack completely.