Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with cooking spray or butter.
In a large bowl, whisk together the flour, baking powder, salt, and granulated sugar.
In a separate bowl, combine the melted butter, milk, and vanilla extract. Pour this mixture into the dry ingredients and stir until just combined. Do not overmix.
Drop spoonfuls of the dough into the prepared baking dish, leaving some space between each dumpling.
In a medium saucepan, combine the brown sugar, water, heavy cream, and cinnamon. Bring to a boil over medium heat, stirring until the sugar has dissolved.
Pour the hot caramel sauce evenly over the dumplings in the baking dish.
Bake in the preheated oven for 30-35 minutes or until the dumplings are golden brown and cooked through.
Serve warm with a scoop of ice cream and a drizzle of custard if desired.