Preheat the oven to 350°F (175°C). Pour the melted butter into a 9×13-inch baking pan, tilting to coat the bottom evenly.
Prepare the batter by whisking together the milk, vanilla extract, and sugar in a large bowl. Add flour, baking powder, salt, and cinnamon, stirring until just combined.
Assemble the cobbler by spooning the batter evenly over the melted butter without stirring. Sprinkle the brown sugar over the top, then gently pour the hot water over everything—do not mix.
Bake in the preheated oven for 30–35 minutes, or until the top is golden brown and mostly set.
Top the cobbler immediately after baking by combining the sugar and cinnamon in a small bowl and sprinkling over the hot dessert.
Cool slightly before serving. Enjoy warm, ideally with vanilla ice cream.
Notes
Storage: Cover and refrigerate for up to 4 days.
Freezing: Freeze in an airtight container for up to 2 months. Thaw before reheating.
Serving Tip: Drizzle with caramel sauce or top with whipped cream for extra indulgence.