What cookie has a depression filled with jam or jelly?

A cookie with a depression filled with jam or jelly is a thumbprint cookie.

The name comes from the small well traditionally pressed into the center of each round of dough with a baker’s thumb. The indentation holds a spoonful of fruit preserve, most commonly raspberry, though strawberry, apricot, and other flavors are also used. The base is often buttery and shortbread-like, sometimes rolled in chopped nuts or sugar before baking.

A closely related Swedish cookie is called hallongrotta, meaning “raspberry cave.” Hallongrottor are commonly filled with raspberry jam and are known as thumbprint cookies in the United States. Similar versions have other regional names, including jam drops, thimble cookies, and Hussar balls.

The defining feature is the indentation and filling, not one exclusive dough recipe. Some modern thumbprints use chocolate, caramel, or other fillings, while the related shortbread cookie is usually unfilled. That is why “shortbread” is a possible description of the texture or base, but not the canonical name for the jam-filled cookie.