Dark Chocolate Cranberry Orange Slice & Bake Cookies

In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl using a handheld electric mixer, combine the butter, orange zest, and sugar and beat on medium-high speed until pale and fluffy. Add in the vanilla. Add in the egg and beat until combined. Add in the flour and dried cranberries and beat until just combined. Your dough should be stiff. 
Sprinkle 2 Tablespoons of flour over a clean work surface. Scrape the cookie dough onto the surface and gently knead it for 30 seconds. Divide the dough in half, then roll each portion of cookie dough into a log that's roughly 2" in diameter. Roll each log in turbinado sugar, if using. Then wrap each log tightly in plastic wrap and refrigerate for at least 3 hours (or up to 5 days).
When you're ready to bake, preheat the oven to 350 degrees (F). Line a large baking sheet with parchment paper or a Silpat baking mat.
Remove the dough from the fridge and place it on a cutting board. Using a sharp knife, slice the logs of cookie dough into 1/4" rounds.
Place the cookies 1/2" apart on the prepared baking sheet, and bake for 10 to 12 minutes, or until lightly golden.
Remove the oven and place the pan on a cooling rack. Cool for at least 15 minutes before removing. 
In the meantime, make the chocolate coating. 
Melt the chopped chocolate in a double boiler or in the microwave. If using the microwave method, place the chopped chocolate in a medium heat-proof bowl. Melt in the microwave, on low power, in 15 second increments, stirring after each increment until completely melted and smooth.
Dip each cookie halfway into the chocolate then return to the lined baking sheet.
Sprinkle wet chocolate with with turbinado sugar and additional orange zest, if desired.
Allow the chocolate to set before serving. To speed this up, place the baking sheet into the refrigerator.
Once set, serve and enjoy! These are really good with coffee or tea.