Chocolate Dipped Orange Shortbread Cookies

to make the orange sugar

1. Add the sugar and the zest to the bowl of a food processor and pulse/process until combined.
2. The zest should be finely ground and the sugar will be moist and pale orange.

to make the cookies

1. To the orange sugar in the processor, add the flour, butter, salt, and extract. Pulse to combine, then run the machine until the dough comes together into a ragged clump. This should take under a minute.
2. Turn the dough out and bring together with your hands so there are no crumbly parts left. Divide in half and form 2 logs of dough, about 12 inches long each. Wrap in plastic and refrigerate until firm, about 2 hours.
3. Preheat oven to 350F. Line baking sheets with parchment paper.
4. Slice the logs of dough into 1/2 inch slices and place, 2 inches apart, on the cookie sheets.
5. Bake the cookies for 10-12 minutes, until just turning golden on the very edges, but still pale on top. Longer cooking will result in a crisper cookie, while shorter cooking time will yield a softer cookie.
6. Let the cookies cool completely on a rack before dipping.
7. Melt the chocolate in a double boiler or in the microwave, starting with one minute, then in 15 second bursts, stirring well in between.
8. Dip each cookie half-way into the chocolate, and then set on parchment paper to harden up. Sprinkle with more orange zest, if desired.