In the bowl of an electric mixer cream together butter and sugar.
Add in eggs and vanilla and continue mixing until well incorporated
In a separate bowl mix flour, salt and baking powder.
Add the flour mixture into the butter mixture a little at a time mixing between additions, until all of the flour is incorporated.
Remove the dough from the bowl and divide it in half.
Add about ¼ tsp orange gel food coloring to one half and knead until the color is evenly distributed.
Repeat with the other half of the dough, adding about ¼ tsp black gel food coloring.
Place black dough on a piece of parchment or wax paper and roll out into an approximately 9x15 rectangle. Place on a baking sheet and set aside.
Repeat with the orange dough rolling it out on parchment or wax paper.
Keeping the dough on the parchment place it on top of the black dough and place the baking sheet in the refrigerator for 15-20 minutes.
Remove dough from the refrigerator. Carefully remove the orange dough from the parchment paper and lay it on top of the black dough lining up the edges as best as possible.
Using a sharp knife trim the edges of the dough to make a rectangle.
Starting with the shorter end of the rectangle carefully roll up the dough you can use the parchment paper to help. Put gentle pressure on the dough as you roll it so that it sticks together nicely.
Wrap the rolled dough in parchment or wax paper and refrigerate at least 2 hours.
When ready to bake-
Preheat oven to 350 and line a baking sheet with parchment paper
Unwrap dough and place on a cutting board.
Using a sharp knife slice dough into ¼ inch slices and place on prepared baking sheet.
Bake for 10 minutes, remove from oven and allow to cool for 1-2 minutes before removing from baking sheet to a metal cooling rack.
Store in an airtight container.