Mix egg yolk, caster sugar, lemon juice, and cornstarch evenly
Boil milk and lemon zest, then turn off the heat. Pour into the egg yolk mixture while stirring quickly. Strain the mixture back into the pot and stir until thickened. Let it cool
Mix cream cheese and caster sugar evenly, then add whipping cream and lemon custard sauce. Stir until smooth
Mix all glutinous rice flour, cornstarch, caster sugar, and milk thoroughly, sift, cover with plastic wrap, and poke a few small holes
Steam over high heat for 25 minutes. While hot, mix in the butter until uniform, and add a drop of food coloring. Stretch the dough repeatedly until elastic
Knead into small dough balls, coat with cooked glutinous rice flour, roll out into round sheets, place in molds, fill with filling, seal tightly, and trim off excess dough
