Line a 8 1/2- by 4 1/2-inch loaf pan with plastic, so there’s a fair amount of overhang.
Add the malted milk powder and salt to a bowl. Add a splash of cream and whisk. Add another splash of cream and whisk. Continue this until you’ve added all the cream. (This ensures that the malted milk powder gets evenly distributed and doesn’t get all lumpy and weird.) Continue to whip the cream until stiff peaks form. (A balloon or cage whisk helps, if you have one.)
Add a single layer of wafers to the bottom of the loaf pan. Top with a layer of whipped cream. Add a single layer of bananas. Top with a layer of whipped cream. Repeat this until you’ve used all the cream—making sure to end with the cream. If it starts to rise above the loaf pan, that’s fine! Even good. Fold the extra plastic over the icebox cake. If it doesn’t completely cover the surface, add more plastic wrap.
Chill in the fridge for at least 12 hours or up to 36.
To unmold, peel away the plastic from the top. Carefully—but confidently—turn the loaf pan onto a plate or serving platter. Peel away the plastic. Slice into thick slabs and eat cold.
Emma is the food editor at Food52. Before this, she worked a lot of odd jobs, all at the same time. Think: stir-frying noodles "on the fly," baking dozens of pastries at 3 a.m., reviewing restaurants, and writing articles about everything from how to use leftover mashed potatoes to the history of pies in North Carolina. Now she lives in Maplewood, New Jersey with her husband and their cat, Butter. Stay tuned every Tuesday for Emma's cooking column, Big Little Recipes, all about big flavor and little ingredient lists. And see what she's up to on Instagram at @emmalaperruque.