Between their bejeweled appearance and rich, buttery flavor balanced by tart jam, thumbprint cookies are the stars of any cookie plate. June’s version adds almond flour and extract to amp the crumbly nuttiness of the cookie base, making stone fruit jams like cherry or apricot a particularly good match for flavor contrast. That said, you can use any jam you wish, or even substitute vanilla extract if you prefer it. Orange zest adds a nuanced floral note and a touch of sophistication to these delicious cookies.