Topping:

Combine topping ingredients in a small bowl. Stir and set aside.

Muffins:

Preheat oven to 350°F. Grease muffin pan and set aside.

In a large bowl, mix together flour, sugar, baking powder, baking soda, salt, cinnamon, and nutmeg.

In another large bowl, mix together grated apple, eggs, oil, and walnuts. 

Add apple mixture to flour mixture, stirring to just moisten dry ingredients. Add coconut, and stir to incorporate.

Divide batter among muffin cups and drop crumbles of topping mixture over top of batter.

Bake at 350°F for 15 to 20 minutes for regular-sized muffins (20 to 25 muffins for large), or until tops spring back when lightly pressed and a wooden skewer inserted into the center of the muffin comes out clean.

Cool pan on wire rack 10 minutes, then turn muffins out and cool on the rack.

Source: canolainfo.org