Cream together the butter and sugar, followed by the egg.
Mix in the flour, baking powder and nuts. Combine. (If the mixture is on the dry side, add a spoonful or two of cold water)*.
Take a heaped teaspoonful of the mixture, roll into balls and place onto the baking sheet. Gently press with a fork to flatten the cookie dough balls a little.
Bake for 15-20 minutes in the preheated oven until the cookies are light golden.
Let cool for about 5 minutes, then transfer onto the metal rack to cool completely.
* I've also used a different method - combined all the dry ingredients (buckwheat flour, sugar, baking powder), added the grated softened butter and the egg, and simply mixed everything and rolled into walnut-sized balls.