Preheat oven to 430 degrees.

Dissolve yeast into warm milk in a mixing bowl.

Add sugar, salt, cardamom, and one egg and mix well.

Add half of the flour and stir into a soft dough.

Mix softened butter into the dough and add as much of the remaining flour as needed until the dough no longer sticks to the bowl or fingers.

Cover the mixing bowl with a kitchen towel and leave the dough to rise in a warm place for at least 30 minutes.

Pour the dough onto a floured baking board and knead well.

Form a long \"sausage\" and cut into 20 pieces.

Roll pieces into bun shapes and place on baking trays covered with greased waxed paper, leaving some space to allow the buns to rise without sticking to one another.

Let the buns rise for 30 minutes.

Brush the buns carefully with the other (beaten) egg.

Press down the centers of the buns lightly with your thumb to form a hole.

Fill each hole with 1 teaspoon of butter and 1 teaspoon of sugar.

Bake the buns at 430 degrees on the middle rack for 10 - 15 minutes, until golden brown.

Set aside to cool.