Preheat oven to 375º.
Sprinkle the chopped cranberries with the granulated sugar.
Mix oatmeal with yogurt. Add egg, brown sugar, oil and orange zest, stir to combine. Combine flour, baking powder, baking soda, and salt. Fold in until just combined. Fold in the cranberries and apple pieces.
Spoon into a greased muffin tin. If using paper liners, spray the inside of the liners with vegetable spray.
Bake 20-25 minutes or until toothpick inserted comes out clean.