Divide the egg yolks and egg whites. Add a pinch of light brown sugar to the egg whites and whip. Add in the sugar over two turns with a tablespoon during the process (2 tablespoons total), and whip until the point where peaks form. *Please use an egg beater to turn it into a meringue with a fine consistency if you are using an egg beater.

Add the skim milk powder to Step 1 one tablespoon at a time. Lightly whip between each turn, lightly stirring so as not to pop the bubbles. : This will become overwhipped even when using a hand mixer at the lowest setting, so please don't use it. *It will become a thick meringue like shown in the photo if you do.*

Whip the egg yolks in a separate bowl until they turn white and thicken, then add in the yogurt, condensed milk, and flour, and mix well.

Add half of the meringue from Step 1 to Step 3, mix well with an egg beater, add in the remaining amount of meringue, stir with a rubber spatula without popping the bubbles, and pour into the mold.

Bake in an oven preheated to 170°C for 30 minutes, cover with aluminum foil to keep it from burning, bake for an additional 30 minutes at 170°C, let cool in the oven until the residual heat resides, and it's done.

This is the tea bag box I used when I first tried this. It holds 50 tea bags and is 12 x 15 cm. I spread out a cooking sheet inside and used it.

Several people have told me that it swells up a lot and then shrivels. I understand why now, so I added notes to Steps 1 and 2. This one in the photo has swollen a lot. (And it shrivelled later). This is the photo of a failed attempt.