Palmier cookies, also known as elephant ears or butterfly cookies, have just 3 ingredients: puff pastry, sugar, and salt.
Whisk together the sugar and salt, then sprinkle some of the mixture on a surface. Unroll the puff pastry sheet on top of the sugar. Sprinkle another handful of sugar on top and press it into the dough. Then, fold the right and left edges of the dough in half.
Sprinkle more sugar on top. Fold both sides inward again. Finally, fold the entire dough in half. Sprinkle the remaining sugar and press into the dough. Then, place it in the fridge.
Slice the cookies and place them on a baking sheet. Bake and let cool.