Preheat the oven to 350 F. Grease and flour a 9-inch round baking pan.
To make the streusel, stir sugars and cinnamon together.
Add melted butter, and then stir in the flour. Mix well and set aside.
To make the cake, beat butter and sugar together on high speed for 4-5 minutes, or until light.
Reduce the speed to low and add the eggs 1 at a time.
Mix in vanilla and Greek yogurt.
Add flour, baking powder, baking soda, and salt, and stir until just combined.
Fold in the blueberries.
Pour batter into the prepared pan.
Crumble the topping evenly over the batter.
Set baking pan on a baking sheet, and bake for 40-50 minutes, or until a wooden toothpick comes out clean.
Cool completely, and dust with powdered sugar just before serving, if desired.
The blueberries sink to the bottom of this coffee cake and form a nice sweet layer along the bottom. If you want the keep the berries from sinking, toss them with a tablespoon or so of flour before you fold the blueberries into the batter.