Cream the butter and sugar. In a large bowl, beat the softened butter and granulated sugar with a hand mixer or stand mixer on medium speed until light and fluffy, about 2–3 minutes.

Add egg yolk and extracts. Mix in the egg yolk, vanilla, and almond extract until smooth. Scrape down the bowl so everything combines evenly.

Mix the dry ingredients. In a separate bowl, whisk together the flour and salt. Add to the wet ingredients and mix on low just until a soft dough forms. Don’t overmix.

Chill the dough. Cover and chill for 20–30 minutes. This helps the dough firm up so the cookies hold their shape.

Preheat and prep. Heat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Shape the cookies. Scoop 1-tablespoon portions of dough and roll into smooth balls. If you like, lightly brush with the reserved egg white and roll in sugar or chopped nuts for extra texture.

Make the indent. Place the balls on the baking sheets, spaced about 2 inches apart. Use your thumb, the back of a rounded teaspoon, or the end of a wooden spoon to make a small, deep well in each cookie. If the edges crack, gently press them back together.

Fill with jam. Stir the jam to loosen it. Spoon about 1/2 teaspoon into each indentation. Don’t overfill; jam expands slightly as it bakes.

Bake. Bake for 11–13 minutes, rotating the pans halfway through. The cookies should be set and barely golden on the edges.

Cool and finish. Let the cookies rest on the baking sheet for 5 minutes, then transfer to a rack to cool completely. Dust with powdered sugar or drizzle with melted chocolate if you’d like.