Preheat oven to 400°F. Grease a 12 cup muffin tin or line with paper muffin liners.
In a medium bowl whisk together dry ingredients. Add oil, egg and milk and stir just until combined. Fold in apples. Divide batter between the 12 muffin cups.
In a small bowl, mix topping ingredients, blending together with a pastry cutter or fork. Sprinkle over unbaked muffins.
Bake 15 to 20 minutes, or until a toothpick inserted in center of muffin comes out clean.