• Preheat oven to 350°. Prepare an 8x8 or 9x9 square pan by lightly coating with cooking spray and then lining with parchment paper.
  
• In a small bowl, sift gluten free flour blend, guar or xanthan gum (don't use if it's in your blend), baking powder and salt.
• In a stand mixer using a paddle attachment, combine butter and sugar. Add egg and vanilla extract until well-blended.
• Add flour mixture to butter and eggs and mix until all of the flour is incorporated. Remove ⅔ of dough and set aside.
• With ⅓ of dough in mixing bowl, add yellow food coloring until you reach your desired color. Remove from bowl and gently press into the bottom of your prepared baking dish. Wipe bowl and paddle clean if necessary.
  
• Put ⅔ of dough back in mixing bowl and add orange food coloring until you reach your desired color. Gently press the orange dough on top of the yellow dough.
  
• Bake for 20-22 minutes if using an 8x8 pan, 18-20 minutes if using a 9x9 pan. The cookie bar will be slightly browned on top, but shouldn't jiggle in the center. Remove from oven and cool completely. Be careful not to remove from pan before cooling as the cookie may break.

Frosting:

• In a stand mixer with the whisk attachment, cream the butter until light and fluffy. Slowly add powdered sugar and heavy cream on low speed. Increase speed once everything is mixed in and mix until well combined. Add vanilla extract.
• Carefully spread frosting over cookie bar and allow to set until frosting is mostly hardened. This shouldn't take too long, maybe 20 minutes or so. Note: if you want to add sprinkles, do so very quickly after frosting as it hardens fairly quick.
• Cut your bars into three equal strips. Then, cut triangles out of each strip.
• Store in an airtight container.