Preheat your oven to 375℉.
Whisk together the flour, baking powder, and salt in a medium bowl.
In the bowl of a stand mixer, cream together the butter and sugar until light and fluffy (about 3 minutes).
Add in the eggs and extracts and mix again until everything is well incorporated, scraping down the sides as needed.
Alternate adding in the flour mixture and milk, using a spatula to fold everything together.
Gently fold in the frozen blueberries before transferring the batter to a lined 9x9 pan.
Mix together the crumb topping ingredients before sprinkling it over the cake. You can also top with turbinado sugar for some extra crunch.
Bake for 30 minutes or until a toothpick inserted into the center comes out clean.
Cool in the pan for 20 minutes before transferring to a wire rack to cool completely.
When the cake has cooled, mix together the icing ingredients.
Drizzle the icing over the cake and serve!