After several attempts at various recipes, I finally found Sweetapolita's and won't use anything else. The only modification I made was to substitute Cacao Barry Cocoa Powder Extra Brute for Hershey's Dark Chocolate Cocoa Powder (for no reason other than it was all I could find locally).
I decorated the cookies above using my FAVORITE ROYAL ICING recipe. The colors were achieved using Americolor Soft Gel Paste in Bright White, Royal Blue, Sky Blue, and Teal.
DARK CHOCOLATE SUGAR COOKIES
6 cups all-purpose flour, sifted
1 1/4 cups dark cocoa powder
1 teaspoon salt
2 cups unsalted butter, softened
2 cups sugar
1 cup light brown sugar
2 teaspoons vanilla extract
In large bowl, sift together flour, cocoa powder, and salt. Set aside.
In the bowl of an electric mixer fitted with the paddle attachment, cream butter and sugars until fluffy and pale (about 5 minutes). Beat in eggs one at a time until just combined.
Add flour mixture and mix on low speed until thoroughly combined. Add vanilla and blend.
Remove 1/2 of dough from bowl, make a ball, and place on a large piece of plastic wrap on counter. Wrap the sides of wrap over the ball, then press down with the palm of your hand and make a disc about 2" thick. Finish wrapping the disc with the plastic wrap. Repeat with 2nd half of dough. Chill both discs of dough for about 45 minutes.
Remove one disc and remove plastic wrap. Place on top of a large piece of parchment paper. Place another large piece of parchment paper on top of dough and roll. You want these cookies to be about 1/4" thick.
Preheat oven to 325F.
Slide your parchment paper and dough onto a cutting board and refrigerate for 10-15 minutes.
Remove from fridge and cut shapes using the cutters of your choice. Place cutouts on cookies sheet lined with parchment paper. Freeze sheet (with cookies) for 15 minutes before baking.
Bake 16-18 minutes (until cookie edges are just crisp).
Cool sheets on wire racks for 10 minutes, then gently remove cookies and place on wire racks to finish cooling.