Separate the dough into two rectangles along the perforated edge (4 triangles to a rectangle).
Working on one rectangle at a time (half the tube), press all the seams together to seal.
Sprinkle 1 tablespoon of granulated sugar over one side of the crescent rectangle, press lightly with you hands to adhere. Gently flip over.
To make rainbows
Place the rectangle so that longer side faces you.
Sprinkle sugars in vertical rows in the colors of the rainbow: red, orange, yellow, green, blue, purple.
Preheat oven to 375°F
Roll up each side so that the two rolls meet in the middle. Wrap in plastic and chill for at least 1 hour.
Line two cookie sheets parchment paper.
To bake the rainbows: Slice the dough 1/2” thick. Place on cookie sheets, 2” apart. Bake for 7-8 minutes, until the bottoms start to get golden. Let cool on cookie sheet for just a few minutes, then run a spatula underneath so the melted sugar doesn’t stick.
Let cool on cookie sheet for just a few minutes, then run a spatula underneath so the melted sugar doesn’t stick.