Put the margarine (or softened butter) and sugar into a bowl, then cream.
Add condensed milk to Step 2, and mix some more.
Add sifted cake flour into Step 3, and mix.
Roll the Step 4 dough into a ball.
Wrap the Step 5 dough with plastic wrap, and shape into a roll. Chill in the freezer for 30-60 minutes to harden.
When Step 6 is hardened, take it out from the freezer, and cut it into about 5 ~ 7 mm slices.
Place Step 7 on a baking sheet lined with parchment paper.
Bake in the preheated oven at 170℃ / 340℉ for 13 ~ 16 minutes, and it's done.
Story Behind this Recipe
I had a lot of leftover condensed milk, so I put it in the cookies. They were very delicious.
The baking time differs depending on the oven, so check on them occasionally. If you don't have time, you can skip putting the dough into the freezer after Step 3, and cut out shapes with cookie cutters. It's a little bit hard to handle, so I suggest you do that on plastic wrap.