Make the cookie dough:

1. In a small bowl, mix together the flour, salt, and baking powder, set aside.
2. Add the softened butter and sugar to a separate large bowl or bowl of a stand mixer. Beat the softened butter and sugar together, using a stand mixer or hand mixer, until smooth.
3. Add the egg, vanilla, and black food coloring (if using) to the butter and sugar mixture. Mix on medium speed until smooth and evenly incorporated. If using the black food coloring, the mixture should be very black. If not, add a bit more food coloring and mix again.
4.  With the mixer on low speed, gradually add in the dry ingredients and mix until evenly combined. If needed, switch to mixing the dough with a wooden spoon. Scrape down the bowl occasionally while mixing.
5. Split the dough into two equal pieces and wrap each half in plastic wrap, shaping it into a disk. Refrigerate for at least 1 hour or up to 3 days.

Shape and bake the cookies:

1. Preheat the oven to 350 degrees F (177 degrees C).
2. Remove half of the dough from the fridge. Set a large piece of parchment paper on a work surface. Very generously sprinkle the paper with granulated sugar and place the unwrapped dough on top (see note 2). Sprinkle the top of the dough with sugar and roll out to about 1/4 inch thickness. If the dough is too firm to roll out, let sit for 5 minutes and then try again.
3. Use a 4.5 inch round cookie cutter to cut the dough into circles. If needed, use a thin metal spatula or metal dough scraper to gently remove the circles from the work surface. Place the large circles onto a baking sheet lined with parchment paper or a silicone baking mat. 
4. Using a cookie cutter that is small enough to fit inside the larger circle without touching the sides, cut shapes into the center of each circle and remove the dough from inside. (You can bake the center shapes as-is or re-roll them into more circles.) If desired, smooth out any rough edges of the cutouts with a butter knife.
5. Place one unwrapped Jolly Rancher into the center of each cutout.
6. Repeat steps 2 - 5 with the remaining half of the dough. Bake the cookies for 9 - 11 minutes, or until the candy has fully melted and the edges of the cookies are firm to the touch.
7. Leave the cookies on the baking sheet until the candy has solidified, about 10 minutes. Remove to a cooling rack to finish cooling.

Decorate the cookies (optional):

1. When the cookies are fully cooled, use the cookie icing to pipe designs onto the cookies.
2. Allow the icing to harden fully before storing in an airtight container.