Preheat oven to 350 degrees Fahrenheit.

Add all the muffin ingredients to a bowl in the order listed, aside from the apples, and mix until combined. Then, fold in the diced apples.

Divide the batter evenly between 12 lined or greased muffin cups.

Mix all the crumb topping ingredients together until crumbs form, then sprinkle over the muffins. I sprinkled some Turbinado cane sugar on top for extra sweetness.

Bake for 25–27 minutes, until a toothpick comes out clean or with a few moist crumbs.