BEAT WET INGREDIENTS: In the bowl of a standing mixer fitted with paddle attachment, combine butter and sugar and beat (cream) on medium speed until light and fluffy –about 2 minutes. Add egg and vanilla and beat for an additional minute.
ADD DRY INGREDIENTS/MIX/REFRIGERATE 1-24 HOURS: On top of the butter mixture, add the flour, baking soda, kosher salt, and orange zest. Stir dry ingredients together lightly and then turn mixer onto low speed, mixing dry and wet ingredients until just well-combined. Shape into a disc, wrap in plastic wrap, and refrigerate for at least an hour/up to 24 hours.
PREHEAT OVEN/ROLL DOUGH INTO BALLS/FILL WITH CRANBERRY JAM: Preheat oven to 350 degrees Fahrenheit. Place rack in the center of the oven. Let jam sit out or microwave and stir briefly to warm up a little before using. Line cookie sheets with parchment paper. Roll dough into 1-inch balls (you may have to let the dough warm up a bit on the counter if it’s been in the fridge overnight) and place 3-inches apart on prepared cookie sheet. Using the end of a wooden spoon (1/2-inch in diameter) or your thumb, make an indentation in the center of each cookie about ¾ of the way through the cookie, rerolling if the dough cracks. Using a 1/2-teaspoon measuring spoon (or other small spoon), fill with jam, being careful to not overfill or the cookies will spread, and the jam will escape.
BAKE/COOL: Bake one sheet at a time 11-13 minutes OR until bottoms of cookies are just golden. Cool on sheet on rack 2-5 minutes before transferring to rack to cool completely.
DRIZZLE WITH MELTED CHOCOLATE/LET DRY: Heat the chocolate on 50% power in the microwave for one minute and then stir or whisk until smooth. If needed, heat again for 10-seconds at a time until chocolate is melted. You can also melt chocolate in a heat-proof bowl over simmering water on the stovetop. Using a fork, drizzle chocolate over cooled cookies letting a little chocolate fall back into the cup before gently waving the fork over the cookies. Continue to stir or whisk chocolate to keep it smooth as you decorate the other batches. You can also spoon melted chocolate into a small storage bag, snip a tiny corner, and, squeezing carefully, drizzle chocolate. Let drizzled cookies set several hours drying before storing in an airtight container for up to 3 days (layer with waxed paper), in the refrigerator for a week, or in the freezer for 6 months. If freezing, do not add chocolate drizzle until cookies are thawed.