blueberry buttermilk streusel coffee cake

Ingredients For blueberry buttermilk streusel coffee cake

• 1 1/2 c

  all-purpose flour
• 3/4 c

  granulated sugar
• 1/4 c

  unsalted butter, room temperature
• 1

  egg, room temperature
• 1/3 c

  buttermilk, room temperature
• 1/4 c

  greek yogurt
• 2 Tbsp

  vegetable oil
• 1 tsp

  pure vanilla extract
• 1 tsp

  baking powder
• 1/2 tsp

  baking soda
• 1/4 tsp

  salt
• 1 1/2 c

  frozen blueberries
• optional: powdered sugar for dusting the top of cake
• STREUSEL TOPPING
• 1/2 c

  all purpose flour
• 1/2 c

  brown sugar, firmly packed
• 1 Tbsp

  turbinado sugar (for extra crunch)
• 1 tsp

  cinnamon
• 1/2 stick

  cold, unsalted butter