Step 1

In a large skillet, over medium low heat, stir together the butter, sugar, cinnamon, nutmeg, and rum until the butter melts, sugar dissolves, and everything's evenly combined. Stirring occasionally, bring the mixture to a light simmer.

Step 2

While waiting for the mixture to come to a slow simmer, prepare an 11x7" brownie pan by spraying it with non-stick cooking spray. Place the bananas evenly out into the pan without overlapping.

Step 3

Pour the buttered rum sauce evenly out over the bananas, and set the pan aside.

Step 4

To a large mixing bowl, add the flour, baking powder, sugar, & salt. Whisk together until evenly combined.

Step 5

To the bowl of a stand mixer, add the egg yolks. Beat them at high speed for 2-3 minutes or until smooth and creamy. Reduce the speed to low, and pour in the juice and extract, mixing just until combined. Continuing to let the mixer run, slowly pour in the butter, mixing until combined.

Step 6

A little bit at a time, pour in the flour mixture, and continue until it's all been added and the batter is smooth. Set that mixing bowl aside.

Step 7

To another stand mixing bowl (or in a separate mixing bowl using a hand mixer), add the egg whites and whisk at a medium high speed- just until stiff peaks form. Fold the whipped egg whites into the batter, just until evenly combined.

Step 8

Using a spatula, scrape the batter out of the bowl pouring it evenly out over the bananas. Gently spread to evenly coat the pan.

Step 9

Bake the cake at 400 degrees for 25-30 minutes, or until a toothpick to the center comes out clean. Remove the cake from the oven, and let it cool for 15 minutes. Working quickly, but carefully, turn the cake out onto a serving platter, cutting board, or metal cooling racks. Continue to let the cake cool for another 15 minutes.

Step 10

Use a sharp knife to cut the cake into squares for serving. Serve with a scoop of vanilla ice cream for dessert, or with a hot cup of coffee for breakfast.