Preheat oven to 375 degrees F. Beat the butter and cheese until wellcombined. Mix in the flour, mustard, cayenne and egg white just until a dough forms. Take about 2 Tbsp. of the mixture and shape into a finger. Make a knuckle shape in the centre and slash a few wrinkles into the dough. Place on a non-stick or parchment-lined baking sheet. Repeat with remaining dough. Make an indentation at the end of each finger. Place a half olive into each indentation. Bake 12-15 minutes, until lightly browned on the bottom and cooked through.