Preheat oven to 375 F.

Toss together cheese, flour, mustard and cayenne.

Mix in butter.

Knead with your hands to form a dough.

If the dough feels very dry, add a tablespoon of water.

On a floured surface, roll out half the dough to a thickness between 1/8- and 1/4-inch.

Cut into squares.

Place on ungreased cookie sheets and bake 10 to 12 minutes until lightly browned on the bottom.

Remove to a rack to cool.