01 - Preheat the oven to 375°F. Lightly grease a 2-quart baking dish with butter or nonstick spray.
02 - In a large bowl, gently toss the sliced bananas with granulated sugar, lemon juice, cinnamon, nutmeg, and cornstarch until evenly coated. Arrange the mixture in an even layer across the bottom of the prepared baking dish.
03 - In a separate bowl, whisk together the flour, sugar, baking powder, and salt until well combined.
04 - In a third bowl, whisk the melted butter, egg, whole milk, and vanilla extract until smooth and fully incorporated.
05 - Pour the wet ingredient mixture into the dry ingredients and stir gently with a spatula until just combined. Avoid overmixing to keep the topping tender.
06 - Spoon the batter evenly over the banana filling, spreading it almost to the edges of the dish. Some fruit peeking through is perfectly fine and adds character.
07 - Bake for 35 minutes, or until the topping is golden brown and a toothpick inserted into the crust comes out clean. The fruit filling should be bubbling around the edges.
08 - Allow the cobbler to cool for 10 to 15 minutes before serving. Serve warm on its own or topped with vanilla ice cream or freshly whipped cream.