Vanilla And Blueberry Buttermilk Crumb Cake

Ingredients

• cake
• 2 cups ap flour, plus 2 tbsp
• 1 tsp baking powder
• 1 tsp baking soda
• 1 tsp salt
• 8 tbsp unsalted butter, at room temp
• 1 ¼ cup white sugar
• 2 tbsp fresh lemon zest
• 1 large egg
• 1 egg yolk
• 1 vanilla bean, seeds removed
• 1 cup buttermilk ** if you don’t have buttermilk on hand, just use regular milk with a squeeze of lemon juice added into it**
• 2 cups fresh blueberries
• topping
• 1 cup ap flour
• 1 cup light brown sugar
• 1 tsp sea salt
• 2 tbsp fresh lemon zest
• 8 tbsp unsalted butter, melted