Puff Pastry Cookies

Grate the chilled butter into a bowl, add a cup of flour. Rub together with your hands into crumbs.

Warm the kefir slightly, add baking soda and salt, and stir.

Add the kefir and egg to the butter crumbs. Gradually adding the remaining flour, knead a soft, non-stiff dough.

Filling: mix flour, sugar, butter, and cinnamon. Rub together into crumbs.

Roll the dough out thinly into a rectangle. Spread half of the filling over it, pressing it down with your hands. Fold the dough into an envelope.

Roll out again, spread the remaining filling, and fold into an envelope. Roll out the envelope and cut into individual pieces.