Mix mashed potatoes, potato water, and yeast in a bowl.

Add milk and let stand for 1 hour.

Add melted lard, sugar, salt, and beaten egg.

Gradually add enough flour to form a stiff dough.

Knead the dough well.

Let the dough rise until it doubles in bulk.

Roll out the dough to approximately 1/2 inch thickness.

Cut the dough into rounds using a cookie cutter or glass.

Place the dough rounds on a greased baking pan.

Let them rise until light.

Make a depression in the center of each round.

Fill each depression with your favorite butter or preserves.

Bake at 350°F (175°C) for 20 minutes.