Preheat your oven to 350°F. Grease a 1 1/2 to 2-quart baking dish with 1 Tbsp of melted butter and set it aside.

In a large skillet, melt 4 Tbsp of butter over medium heat. Add the heavy cream, corn syrup, and brown sugar, stirring occasionally until the sugar dissolves. Remove the skillet from the heat, then stir in the vanilla extract.

Gently add the banana slices, tossing to coat them evenly. Pour the banana mixture into the prepared baking dish.

In a medium-sized bowl, combine the oats, brown sugar, flour, cinnamon, and salt. Use a pastry blender to cut in the cold cubed butter until the mixture looks like coarse crumbs. Stir in the walnuts.

Sprinkle the topping evenly over the bananas. Bake in the preheated oven for 30 to 40 minutes or until the topping is golden brown and the banana mixture is bubbly.

Let the dessert cool for about 5 minutes before serving with a generous scoop of vanilla ice cream.