Preheat oven to 400F, and put 12 cupcake liners in your cupcake pan
Mix dry ingredients in large bowl. Mix wet ingredients (except berries) in a separate bowl.
Pour wet mixture into the dry, and mix until just combined. Add in blueberries.
Combine the crumb topping ingredients (all except the oil) in a separate bowl. Add the oil, and toss with forks, until it looks crumbly. The crumbs should be the size of an eraser tip.
Fill cupcake liners to 2/3 full with blueberry batter. Top each muffin with 1 tablespoon of crumbs.
Bake for 24 minutes, till a toothpick stuck into the center comes out clean.
(Optional) Mix icing ingredients together, and drizzle on top of muffins