01 - Preheat oven to 350°F. Grease an 8-inch square baking dish with butter or nonstick spray.
02 - In a large mixing bowl, gently toss the sliced bananas with granulated sugar, brown sugar, melted butter, lemon juice, cinnamon, nutmeg, salt, and vanilla extract until evenly coated. Spread the mixture into the prepared baking dish in an even layer.
03 - In a separate bowl, whisk together the flour, sugar, baking powder, and salt. Pour in the milk and melted butter, stirring until just combined. Be careful not to overmix — a few lumps are fine.
04 - Spoon the batter evenly over the banana filling, gently spreading it to cover most of the surface. The batter will spread further as it bakes.
05 - Bake for 35 to 40 minutes, or until the topping is golden brown and a toothpick inserted into the crust comes out clean.
06 - Let the cobbler cool for 10 to 15 minutes before serving. Serve warm on its own or topped with vanilla ice cream or freshly whipped cream.