Buttermilk Blueberry Breakfast Cake

Name: Buttermilk Blueberry Breakfast Cake
Prep time: 10 min
Cook time: 50 min
Total time: 1 h
Cuisine: American
Ingredients: 1/2 cup of unsalted butter (softened); 3/4 cup + 2 tbsp white sugar; Zest of one lemon; 1 egg (room temperature); 1 teaspoon of vanilla extract; 2 cups of flour (divided); 2 tsp baking powder; 1 tsp salt; 1/2 cup of buttermilk; 2 cups of fresh blueberries; 1 tbsp white sugar (for the top)