Preheat oven to 350°F and line a square 8x8 baking pan with parchment and butter or oil spray.
With an electric mixer, cream together butter and sugar until light and fluffy.
Add in the egg and vanilla.
In a separate bowl combine flour, baking powder and salt.
Gradually add the dry ingredients into the wet ingredients until they are all well incorporated.
Divide the dough in half.
Add yellow food coloring to one half of the dough and knead until the color is even throughout.
Repeat with the other half of the dough and orange food coloring.
Press the yellow dough into the bottom of your prepared pan.
Place the orange dough on a piece of parchment or wax paper and roll or press it out into an 8x8 square. Carefully place it on top of the yellow dough in the pan and gently press it into place.
Bake for 18-22 minutes or until just set. Don’t overbake or the cookies will be dry.
Place on a cooling rack to cool completely before frosting.
To make the frosting
Place butter in a mixing bowl and cream with an electric mixer.
Add in vanilla and continue beating.
Add in cream and half of the powdered sugar and mix. Add remaining powdered sugar and salt, beat until all ingredients are well incorporated and frosting is smooth.
Spread frosting across cooled cookie bars.
Decorate with candy corn and orange and yellow sprinkles.