Preheat oven to 350°F. Brush a 1 1/2- 2 quart baking dish with 1 Tbsp melted butter. Set aside.
Bananas: On the stove top using a large 12-inch skillet, melt reserved 4 Tbsp butter with heavy cream, corn syrup and brown sugar over medium heat. Heat stirring, just until sugar has dissolved. Remove from heat, add rum and vanilla. Mix well. Add bananas, tossing until coated.
Pour the mixture into prepared baking dish. (The skillet should be big enough to double as a mixing bowl).
Topping: In a medium-size mixing bowl, toss together oats, brown sugar, flour, cinnamon and salt.
Use a pastry blender to cut cold butter into dry ingredients until it resembles cornmeal. Add walnuts, toss to evenly distribute. Sprinkle evenly over bananas.
Place into oven baking for 30-40 minutes or until golden and bubbly.
Let stand for 5 minutes then serve with a big scoop of vanilla ice cream.
Notes
Choose Firm Bananas - When choosing bananas for this recipe, choose firm ripe bananas, not overripe or soft like you may pick for banana bread. If you use soft bananas they'll just turn to mush when baked.
Sugar - You can use light brown sugar or dark brown sugar for a stronger molasses flavor.
Nuts - You could use pecans in place of walnuts, if that's your preference. You'll also need vanilla ice cream for serving.
Rum - What's the best rum for bananas foster? A robust dark rum works best. You could also use banana rum to amp up the banana flavor.
Rum Substitution - If you'd like to make this without alcohol, you can replace the rum with rum extract, if preferred. You'll need 1-2 teaspoons. When doing so, add 2-3 tablespoons of heavy cream.
Use Quick Cooking Oats - For this crisp recipe you'll need quick cooking, not instant oats. If you have old fashioned oats on hand, pulse them a couple of times in a food processor to chop them a bit smaller being careful not to grind them too fine.
Pan Options - When using an oven safe skillet, you may opt to prepare the bananas on the stovetop then bake the bananas foster crisp in the same skillet instead of transferring to a baking dish. When doing so you'll be starting with a hot skillet so the bake time may be less, adjust accordingly.
How Do You Serve Bananas Foster Crisp? This dessert is meant to be "saucy" just like the original version making it perfect for serving with a generous scoop of vanilla ice cream or whipped cream.