Preheat oven to 400 degrees. Mix butter
and mashed potato. Sift
in flour add salt and mix by hand. Knead
, wrap and chill for 30 minutes. Roll out dough
to 1/3-inch thick. Cut into 3-inch strips, brush with egg, top with fennel and bake on a greased sheet pan
for 10 to 12 minutes. Sprinkle with salt and pepper.