• Preheat oven to 350 degrees. Place 4 tablespoons of butter into a 9 x 13 pan. Place in the oven to melt. (I do this when the oven is heating up). Once melted remove from the oven and set aside.
  

Brown the butter

• Add 1/2 cup butter to a small saucepan and cook over medium heat until light brown / caramel in color. 5-10 minutes. Make sure to keep and eye on it so butter does not burn. It also helps to use a light colored saucepan for this. Set aside to cool.
  

Make blueberry filling

• In a medium bowl combine blueberries, 1/4 cup sugar and lemon zest, set aside.
  

Make batter

• Meanwhile In a large bowl combine flour, baking powder and salt. Add the milk, the remaining 1 1/4 cup of sugar, vanilla and melted butter into the flour mixture and mix until smooth.
  
• Pour batter into the prepared baking dish.
  

Assemble / Bake

• Drop spoonfuls of the blueberry mixture ontop of the batter.
  
• Sprinkle with 2 tbsp sugar and bake until golden brown and edges are crisp, 45 to 50 minutes.
  
• Cool for 30 minutes before serving and serve with ice cream if desired!