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

Cream the butter and sugar. In a large bowl, beat the softened butter and granulated sugar until pale and fluffy, 2–3 minutes. This step is key for a tender crumb.

Add egg yolk and extracts. Mix in the egg yolk, vanilla, and almond extract (if using) until smooth. Scrape the bowl so everything blends evenly.

Add dry ingredients. Whisk the flour and salt together, then add to the bowl. Mix on low just until the dough comes together. Don’t overwork it.

Chill briefly. Scoop the dough into 1-inch balls (about 1 tablespoon each) and place them on a tray. Chill for 15 minutes. This helps prevent spreading.

Shape the wells. Arrange the chilled dough balls on the baking sheets, spacing them about 2 inches apart. Press a deep indentation into each with your thumb or the back of a 1/2 teaspoon measure. If cracks form, gently pinch them back together.

First bake. Bake for 9–10 minutes until the bottoms are just setting but the tops are still pale. The wells may puff slightly—press them down again gently right out of the oven.

Fill with jam. Stir the jam to loosen it. If it’s very thick, warm it slightly or thin with a little lemon juice. Spoon about 1/2 teaspoon into each indentation.

Second bake. Return to the oven for 4–6 minutes. The edges should be light golden, and the jam should look glossy and slightly set.

Cool and finish. Let the cookies cool on the sheet for 5 minutes, then transfer to a rack. Dust with powdered sugar once cool, if you like.