Preheat your grill or oven to 350F.
Melt 2 tbsp of the butter and coat the bottom of a 10.25 inch cast iron skillet.
In a large mixing bowl, whisk the eggs, 3 Tbsp melted butter, and vanilla.
In another bowl, combine the dry ingredients: semolina and all-purpose flour, baking powder, and salt.
In two or three additions, add the dry ingredients to the egg mixture alternately with the milk, and whisk to combine between each addition.
Pour the batter into the prepared cast iron skillet.
Arrange the fruit on the top of the cake batter in desired pattern, and pour any remaining juice over the top of the fruit.
Top with sparkling or turbinado sugar.
Bake on the grill at 350F for 40-45 minutes, or until a toothpick inserted comes out with just a few crumbs and the edges are golden brown.
Allow to cool before serving and top with a sprinkle of powdered sugar and reserved blueberries, if desired.