Preheat oven to 350 degrees. Grease a 9" x 13" pan.
Combine first 4 ingredients into large bowl. Cut butter into flour mixture until coarse crumbs form using a food processor.
Mix eggs, milk and vanilla in medium bowl then pour into flour mixture. Stir until moistened then fold in blueberries and spread into the prepared baking pan.
Combine topping ingredients in small bowl and sprinkle on top of blueberry coffee cake batter.
Bake 35 minutes. Coffee cake is done when a toothpick comes out clean.
Cool in the pan then serve and enjoy!
Notes
If I want to turn this blueberry coffee cake into a dessert, I combine 1 cup of powdered sugar with 2 tsp milk and 1 tsp lemon juice. Drizzle on top and enjoy!