Beat with a whisk or mixer butter at room temperature with sugar.
Add eggs one by one, each time whipping, then milk, baking powder, vanillin. Flour add as much to get the dough as not too thick sour cream, but not liquid, about 2.5 cups. The dough turns out a little bit with grains, do not be afraid, it should be.
Spread out the paper molds for cupcakes (or silicone) in a suitable form, fill the molds with the dough not to the edges, about 2/3 of the volume.If you want to make with a filling from boiled condensed milk, put 1 tbsp of dough, then 1/2-1 tsp condensed milk, the dough.Bake until ready, about 15-20 minutes at 180-200 degrees.