Puree the banana. Use a food processor or handheld mixer. If it's a bother just mash it up with a fork.
Put the ★ ingredients in a small pan, and mix it up well before starting to cook. If you want a really creamy, smooth texture, I recommend straining the mixture through a sieve at this stage.
Cook over low heat while mixing constantly with a whisk. When it starts to thicken, the hardening process will progress very quickly, so keep mixing!
When the cream is turning glossy and thick, add the banana puree and mix it in well. Turn off the heat and add the butter. Done!
When cooling down the cream, press a sheet of plastic wrap right on the surface of the cream.This prevents the surface from drying out and forming a skin.
All the tablespoon measurements are level tablespoons.
Small whisks and pans make handling the cream easier with this recipe. See the one on the right in the photo. Small whisks are very useful. I bought mine at a 100 yen shop.
If you chill the cream in the refrigerator it will firm up quite a bit, so use as a filling in bread rolls and so on.
By the way, I don't strain the cream since it's extra work, but it still comes out very nicely.
I also have a "strawberry" version in my custard cream series. Recipe ID: 784130.
I also have a "chocolate" version in my custard cream series. Recipe ID: 786886.
Story Behind this Recipe
I love custard cream. I love it as a filling for bread or cream puffs. I like it on its own as a dessert too. I don't like making complicated recipes myself, so I aimed for a simple and easy one.
The key is to keep mixing it with a whisk over low heat. When it starts to thicken it progresses very fast, so if you stop mixing it will become lumpy. The key to a smooth, creamy finish is constant mixing.