Cake: Preheat oven to 375°F. Grease and line three 6-inch cake pan (or two 9-inch) with parchment
Whisk together the flour, baking powder, baking soda, spices and salt in a bowl.
Cream the butter and sugar together in a stand mixer fitted with a paddle attachment until light and fluffy, about 3 minutes.
Beat in the eggs one at a time. Scrape down the bowl after each one. Stir in vanilla. Mix in the flour mixture, alternating with the mashed bananas. (flour, bananas, flour, bananas, flour).
Pour the cake batter into the prepared pans and bake for about 25 minutes or until the tester comes out with a moist crumb, but not wet. Allow to cool.
Buttercream: In the bowl of a stand mixer combine the egg whites and honey.
Put the bowl over a double boiler and stir it with a rubber spatula until the mixture is melted, hot (140°F) and thin.
Put the bowl on the mixer and beat with the whip attachment on medium high speed. Whip until it's light, fluffy, glossy and the bowl feels just about room temperature. If the egg whites are not cooled off sufficiently it will melt the butter when you add it.
Once the egg whites are whipped and cooled, add the butter, 2 tablespoons at a time on medium speed. WARNING: After you have added about half of the butter, it may look curdled and runny, this is normal and you should continue adding the rest of the butter.
Once you have finished adding the butter and it has mixed on medium speed for about a minute the buttercream will be creamy and glossy looking again. Add the espresso and salt.
Honeycomb Candy: Line an 8-inch square cake pan with butter and parchment, making sure the parchment covers the sides and is well buttered, so the honeycomb won’t stick to it. Add the chopped chocolate to the pan. You also want to place the cake pan on a baking sheet, just in case.
In a large pot heat the sugar, corn syrup, honey and water without stirring until the mixture reaches 302°F on a Candy Thermometer. Immediately remove from the heat and stir in the baking soda. It will foam up as you stir. Quickly pour it into the prepared pan and sprinkle the top with the salt. Allow to cool completely. Remove from the pan and break into pieces.
Round Honeycomb Topper: I greased and lined a 6-inch round cake pan, just as I instructed for the square one, then added 4 ounces chopped bittersweet chocolate. When the honeycomb was ready, I poured a portion of it into the round pan and after it cooled I placed the chocolate coated honeycomb on the cake like a crown.