Preheat oven to 375 F (190° C).
In a medium bowl, beat softened butter and sugar together.
Beat in egg yolk and vanilla.
Using a wooden spoon, gradually mix in flour and crushed potato chips until well combined.
Roll dough into 1 1/2 inch (4 cm) balls and place on a greased cookie sheet 3 inches (7.5 cm) apart.
Flatten using the bottom of a glass jar or glass cup.
Sprinkle granulated sugar on top of each cookie and place an almond or pecan into the centre.
Bake for 8 to 10 minutes or until golden brown.
Let cool on a wire rack.