You could do these in any flavor and color, with sprinkles on the outside our without - They really are pretty and make a statement!
For Halloween, I made half the dough vanilla flavored with purple food coloring, and the other half chocolate using King Arthur Flour's black cocoa, along with a tiny bit of black food coloring, to really make them nice and dark.
3 c all-purpose flour
1 1/2 tsp baking powder
1/4 tsp salt
1 c butter, softened
1 c sugar
1/8 tsp Fiori di Sicilia (optional)
1 tsp pure vanilla extract
1 1/2 tsp espresso powder (optional)
2 Tbsp black cocoa (or regular unsweetened cocoa)
food coloring if desired
sprinkles if desired
Cream together sugar and butter, then add the egg and the vanilla and fiori di Sicilia (if using). Add the flour and baking powder and beat together until well mixed. Separate the dough into two equal portions. To one half, add any desired food coloring (if you aren't doing a white swirl). To the other half, stir in the espresso powder, cocoa, and black food coloring if desired.
Pat the doughs out into rectangles, cover with parchment or saran wrap, and refrigerate for at least an hour before rolling. When you roll, the two colors should be rolled separately into thin rectangles of the same size (about 1/8" - 1/4" thick each). I cut the edges to make sure they would be nice and even.
Layer one color on top of the other and roll tightly into a "cinnamon roll" style roll. If desired, coat the exterior of the log with sprinkles. Wrap tightly in parchment paper, and freeze for at least an hour. This log could be frozen much ahead of time, and then you could just cut and bake as desired.
When ready to bake, preheat the oven to 350 F. Remove the log of dough from the freezer and slice into even slices about 1/4" thick with a sharp knife (serrated will probably work better). Place on lined cookie sheets and bake for 9-11 minutes, or until cooked but not overly browned. Remove and cool on wire racks and enjoy.