Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.
In a large mixing bowl, combine the dry ingredients: flour, granulated sugar, baking powder, salt, and ground cinnamon. Whisk until well blended.
Add the wet ingredients: milk, melted butter, and vanilla extract. Stir until just combined.
In a separate bowl, mix together the brown sugar, granulated sugar, and ground cinnamon for the topping.
Pour the batter into the greased baking dish and sprinkle the cinnamon-sugar mixture on top. Carefully pour hot water over the entire dish without stirring.
Bake for 40-45 minutes until the top is golden brown and the edges are bubbly. Allow to cool for 10 minutes before serving.