Use 1 tbs butter, 1 tbs flour to make a quick white roux and add 1/2 cup cold milk to the roux for a classic Bechamel sauce. Let cool.
Combine white sauce with 8 oz (by weight) of cooked, peeled and cooled sweet potato, 2 tbs sugar, 1 tsp cinnamon, 1/2 tsp nutmeg, 1/4 tsp allspice, 1/2 tsp vanilla extract, 2 egg yolks and blend/whisk smooth.
Begin whipping 2 egg whites, add 1/2 tbs sugar when they begin to stiffen, continue whipping and add another 1/2 tbs sugar when it starts to hold a peak and continue to whip until it resembles the sheen and stiffness of shaving cream.
Fold half the meringue into the the sweet potato mixture at a time making sure not to be too aggressive mixing them together. Simply fold until all the white color has turned the same color as the sweet potato mixture.
liberally butter and sugar the bottom and sides of (4) 8 oz baking Ramekins (small, straight-sided bowls), scoop mixture into bowls and bake in 400 degree oven until tops just start to brown ~20-25 minutes.
Present it hot and finished with powdered sugar before it falls, but let cool some before enjoying. Again, the same flavors as Mom’s but now with the lighter texture and elegant presentation.