Preheat oven to 350 degrees. Prepare a bread pan by either spraying with non-stick cooking spray or lining with parchment paper. Set aside.
In a small microwave safe bowl, melt 4 tablespoons butter. Add brown sugar and stir to mix well. Pour into bottom of bread pan and spread so it coats the bottom. Add blueberries on top of butter mixture.
In a small bowl, combine the cornmeal, flour and baking powder. Set aside.
In a stand mixer, cream butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. On low, add in the lemon zest, lemon juice and milk. Mix until well-combined.
Add in the dry mixture and beat until just combined. Pour into the bread pan over the blueberries and smooth out the top.
Bake for about 35-40 minutes until a toothpick inserted in the center tests done. Let cool in pan for 10 minutes and then invert onto a cooling rack to cool completely.
For the glaze, mix 2 teaspoons lemon juice and powdered sugar in a small bowl. You can additional lemon juice, one teaspoon at a time, until it is the right consistency to drizzle over the bread.
You can use frozen blueberries in place of the fresh berries.