Preheat oven to 375°F. In a bowl, mix flour, salt, sugar, baking powder, milk and vanilla extract; stir until mixture forms a smooth batter. Gently stir in butter. Spread batter evenly in a 9-by-13-inch baking dish (it will be a very thin layer) and scatter pineapple chunks evenly over batter.
Bake until pineapple has fallen to bottom of pan and top is puffed and golden brown and springs back slightly when touched in middle, 25 minutes. Cool cobbler slightly and then serve warm with vanilla ice cream or whipped cream, if desired.