Beat the margarine, 1/2 cup (125 g) sugar, 1 egg and salt into foam and sift the flour mixed with the baking powder on top of them. To be able to roll out the dough, add a tiny bit of milk. Spread out slightly more than half of the dough into a buttered and floured form, so as to form a high edge around it.
Beat the strained cottage cheese into foam, remaining sugar and 1 egg. While mixing, add the vanilla and rum. Spread this creamy paste on the dough. Roll out the remaining dough into the shape of a rectangle and smear it with marmalade. Roll it up and slice it. Arrange the rolls loosely atop the cottage cheese and smear with the remaining egg.
Bake in a moderately heated oven for at least 60 minutes. At the beginning of baking, cover with foil, so as to not burn it too quickly. Sprinkle it with powdered sugar.