Preheat the oven to 375 degrees F.
Make the crumb topping by mixing all the ingredients in a bowl until you have a crumbly texture. Set aside.
Mix the dry ingredients in a large bowl.
Mix all the wet ingredients in a bowl.
Add the wet ingredients to the dry and mix. Make sure you don't have any dry flour remaining at the bottom, but try not to overmix the batter.
Spray a 12-cup muffin pan with cooking spray. Divide the batter equally between the 12 cups.
Sprinkle the crumb topping on top of each muffin.
Bake for 20 minutes or until a toothpick inserted in the center of a muffin comes out clean.
Cool on a rack for 10 minutes, then unmold the muffins and serve.