Preheat oven to 350º. Spray a 9-inch springform pan with non-stick cooking spray with flour.
Prepare crumb topping and set aside.
In a small bowl, whisk together flour, baking powder and salt and set aside.
In a large bowl, beat butter and sugar until light and fluffy. Add eggs, vanilla and milk. Mix in lemon zest. Add flour mixture and mix just until combine. Stir in blueberries.
Spread batter evenly into prepared pan. Sprinkle with crumb topping.
Bake at 350º for 45 minutes or until a toothpick inserted into the center comes out clean. About 210 degrees with an instant read thermometer.
Cool 10 minutes, then run a knife around the edge and remove ring. Drizzle icing on cake. Cool completely before serving. (Unless you're like us and would rather eat it hot even though the cake doesn't cut as well.)
In a small bowl, with a fork mix together sugar and flour. Add butter and mix until mixture is sandy and clumps together.*
Whisk together powdered sugar and lemon juice to create a thin glaze.
*If your crumb topping is not crumbly after adding the butter, add a little additional sugar and flour until you get a crumbly mixture.