Step 1

Mix softened butter and icing sugar until creamy. I didn't use a mixer. You can just use a wooden spatula to mix. Add yolk and the mix again. Sift in the milk powder, cake flour, and pinch of salt. Mix to combine. Cover and chill the cookie dough for at least 30 minutes

Step 2

Preheat oven to 300 F (150 C). Lined baking sheet with parchment paper. Use a 1/4 or 1/2 teaspoon (measuring teaspoon) to scoop the dough and roll it into a round ball. I leave it in a round shape as is. You can flatten it slightly and then use a fork to imprint some pattern on the side (to look more like old-school iced gems). Place them on a prepared baking sheet, about 1/2-inch apart. These cookies do not spread much

Step 3

Put in the middle rack and bake for 15 minutes. The cookies will only be "half-baked" at this point. Remove from the oven but keep the oven on and lower the temperature to 250 F (120 C) because we will continue to bake them with the meringue on top. Let the cookies cool down while you prepare the meringue

Step 4

Beat the egg white until foamy on medium speed, about 1 minute and then add the lemon juice and beat for another minute over medium speed. Add 1/4 of the sugar and increase speed to high and continue to beat while adding sugar batch by batch. Beat until the meringue is glossy and has a firm peak. You will see a pointy peak when you lift the meringue up and if you turn the bowl upside down, it will not flop and stays in shape. You are done beating here

Step 5

Divide the meringue into 3-4 equal portions. Add some gel food colors of your choice. I use ube and pandan extract and I leave one uncolored

Step 6

Transfer the meringue to a piping bag fitted with a star nozzle. Pipe the meringue on top of the cooled-down cookies. You might have some extra meringue, which you can just pipe on the baking sheet too as extra meringue cookies (you won't regret it)

Step 7

Bake in the middle rack for 10 minutes. The meringue will still be sticky to touch at this point. Don't panic. Don't try to bake until the meringue are dry because you will be overbaking the cookies. Turn off the oven and leave the cookies in the oven (with the door closed) for 1-2 hours. The residual heat will "dry" up the meringue nicely

Step 8

I left mine for 2 hours. You can even leave them in the oven overnight. If it's humid where you are, you may need longer time as we all know egg white are sensitive to humidity (the humid weather makes it sticky). It's better to let them dry up in the oven then at room temperature if humidity is high where you are. When I open the door to check, the meringue is already dry and all firm up

Step 9

Make sure the cookies are completely cool before you store them. Transfer to jar with a tight-fitting lid and they can be kept for about one week or so (depending on humidity too)