Blend butter, flour, baking powder, garlic, salt and pepper to form crumbly mixture. Add potatoes and mix quickly. Mix in hazelnuts. After a few minutes, roll dough on floured board, fold once and chill for 20 minutes. Knead, roll and chill three more times.

Heat oven to 375. Roll out dough to 1" thick. Cut into 1-1/2" rounds. Criss-cross top of biscuits with knife blade, then brush with egg yolk and water mixture. Place on greased baking sheet and bake for 20 to 30 minutes. Biscuits are done when they're shiny gold.

Hazelnut Industry and The Hazelnut Marketing Board