Step 1

Preheat the oven to 325 degrees F (165 degrees C).

Step 2

Mix butter and powdered sugar together with a rubber spatula until creamy. Add vanilla extract, almond extract, salt, and egg yolk. Mix with the spatula. Add flour and blend until just combined.

Step 3

Use a sorbet scoop to portion dough into 1/2-ounce (1-tablespoon) balls. Roll balls in a plate of white sugar to coat; roll again between your palms. Place several inches apart on a silicone-lined baking sheet. Flatten balls lightly with your fingers.

Step 4

To make shortbread cookies with a little jam, poke a well into each cookie using the end of a thick wooden spoon dusted with powdered sugar or using one of your fingers. Fill cookies with fruit jam. Tap baking sheet against the counter to let jam settle.

Step 5

Bake in the preheated oven until tops are barely blonde and bottoms are slightly golden, about 15 minutes. Let cool on a wire rack before icing.

Step 6

Meanwhile, mix powdered sugar with a little milk until you have a consistency that will hold its shape when piped. Pipe icing on top of cookies in a zigzag pattern. Let sit for 15 minutes before serving.

Step 7

For a more jam-forward cookie, press your thumb into the cookies to make large, shallow indentations. Spoon in jam. Tap baking sheet against the counter.

Step 8

Bake until not quite golden brown, about 15 minutes. Let rest on pan for 5 minutes before transferring a wire rack. Dust with powdered sugar.