How to Make It
Preheat oven to 350°F. Spread sesame seeds in a single layer on a baking sheet. Bake until fragrant and toasted, 10 to 12 minutes, stirring after 8 minutes. Cool 10 minutes on baking sheet.
Beat together butter, both sugars, and orange zest with an electric mixer on medium speed until light and fluffy, 3 to 5 minutes.
Add egg and vanilla, beating on medium speed until combined.
Whisk together flour, cardamom, baking soda, and salt in a bowl. Gradually add flour mixture to butter mixture with mixer running on low speed. Fold in ¾ cup of the toasted sesame seeds.
Shape dough into 26 balls (about 1 tablespoon each). Roll balls in remaining ½ cup sesame seeds, and place 2 inches apart on a baking sheet lined with parchment paper.
Bake until fragrant and golden around edges, 10 to 11 minutes. Let cool on a wire rack 10 minutes before transferring to a plate.