Adjust rack to middle position and heat oven to 350 degrees.

Line a rimmed baking sheet with parchment paper.

Combine strawberries, 1/2 cup of the sugar, and 1/2 tsp. of salt in a bowl.

Whisk water and cornstarch in another bowl.  Add to strawberries and toss until strawberries are evenly coated.

Transfer strawberries to a cast iron pan or a 9*13 baking dish and place on the prepared sheet.

Bake for 50 minutes until bubbling.  Using a rubber spatula scrape down the sides and stir the strawberries 1/2 wat through cooking time.

With 5 minutes remaining prepare the batter.  Whisk flour, baking powder, remaining sugar and 1/2 tsp. salt in a large bowl.  Whisk the milk, hot melted butter and vanilla in another bowl.  Add wet ingredients to dry.  

Remove sheet from oven and stir.

Pour batter over strawberries.  Cover as much as possible.

Bake until golden brown and toothpick comes out clean about 60 minutes.

Let sonker sit for 15 minutes.