Peel the sweet potatoes rather thickly, and cut tinto 1 cm cubes. Leave to soak in water. (You should be left with about 700 g of sweet potato after peeling them).
Drain the sweet potato cubes, cover with plastic wrap and microwave for 8 minutes (if using a 500w microwave).
Whilst they are still hot, strain the sweet potatoes through a strainer (you can use a cheap 100 yen sieve). To prevent the sweet potatoes from cooling, keep them wrapped and pass them through the strainer in small batches.
This is what the sweet potato should look like once it's been sieved. I just threw away any hard bits that didn't go through.
Add butter and sugar to a pan and melt them together over low heat. Just before the mixture comes to a boil, stop the heat. Once the sugar has more or less melted go on to the next step.
Add the sweet potatoes, cream and brandy to the pan. Add the milk bit by bit and keep mixing until it reaches the consistency of anko (sweet bean paste, rather like stiff mashed potatoes).
Shape the mixture into little barrel shapes and place into aluminium foil cups. Glaze with beaten egg and bake for roughly 15 minutes in an oven preheated to 200°C.
Place the baked snacks on a cooling rack, wrap and leave to cool. (Make sure the sweet potato does not dry out too much while baking.)
Story Behind this Recipe
I was able to get some yummy looking sweet potatoes.
Because you cut the sweet potatoes into 1 cm squares and heat them in the microwave, they should be very easy to drain! About 1/3 of the way through straining the potatoes, your sieve or strainer will get blocked up. When this happens, just give the sieve a rinse and the potato should pass through easily again. You can mash the potatoes instead, but if you strain them they'll be much smoother in texture, and have a light, fluffy delicious texture.