Rinse the sweet potatoes. Peel, and slice into 2 cm rounds. Put into a pan with enough water to soak. Cover the pan and heat. When it boils, uncover the pan. Cook until a skewer goes through thoroughly.
Drain in a colander or a sieve.
Return the potato into the pan and mash while hot. Add sugar, butter, and vanilla extract and mix well with a spatula.
Transfer into cups. I was able to make 8 servings in a madeleine mold.
Brush egg yolk for the glaze. Bake in a oven until slightly browned. Finish!
Story Behind this Recipe
My mother used to make this ever since I was a child! This is certainly my favorite family sweets.
Make sure not to overcook the sweet potatoes. It will be too watery when it's too soft, which makes it really runny when you add butter and sugar.