Preheat oven to 350°F (175°C).
Pour melted butter into a 9x9 inch baking dish.
In a mixing bowl, combine flour, sugar, baking powder, and salt.
Whisk in milk and vanilla extract until a smooth batter forms.
Pour the batter into the baking dish over the melted butter without stirring.
Evenly distribute chocolate chips over the batter surface.
Drizzle salted caramel sauce across the top and sprinkle with flaky sea salt.
Bake for 35 to 40 minutes until the topping is golden brown and a toothpick inserted into the cake portion comes out clean.
Remove from oven and let rest for 10 minutes before serving warm.