In a large bowl, combine the flour, baking powder and salt. Mix with a spoon or fork. Set aside.
2 ½ cups (300g) all purpose flour, 1 tsp baking powder, ¼ tsp salt
In a mixing bowl, combine the room temperature butter and sugar, beat with an electric mixer for 90 seconds.
½ cup (113g) unsalted butter, 1 cup (198g) granulated sugar
Add in the egg and vanilla extract and beat for 1 minute.
1 large egg, 1 tsp vanilla extract
Add the flour in thirds, mixing just until the flour is incorporated. The dough will initially look crumbly almost sandy. But continue to mix until the mixture is thick and sticks together. Use your hands to gently knead the dough together at the very end of the mixing process – knead for only 20-30 seconds.
Divide the dough into 2 flat discs, cover each with plastic wrap and place in the fridge for at least 1 hour to chill. The dough can be left in the fridge to chill for up to 2 days.
After chilling, remove one disc and preheat the oven to 350ºF.
On a very lightly floured surface (and I mean minimal) use a rolling pin to roll the dough to 1/4 inch thick. Frequently I will roll my dough on a silicone baking mat to eliminate the need to use flour.
Use cookie cutters to cut out your desired shapes. Remove the dough scraps and use a spatula to transfer the shapes to a baking sheet lined with a silicone baking mat. Bake for 9-10 minutes. If your oven has a hot spot, rotate the cookie sheet half way through.
The cookies will be pale in color – but will continue baking slightly once removed from the oven. Allow the cookies to cool on the baking sheet for at least 10 minutes. Then move to a cooling rack. Repeat the process with the remaining dough. If your dough is out of the fridge for too long, wrap it and chill it in the fridge for 15 minutes.
Allow the cookies to cool completely before frosting them.
Frosting
Place the softened butter in a mixing bowl, beat using an electric mixer for 90 seconds.
1 ½ cups (339g) unsalted butter
Gradually add the powdered sugar, I usually do 2 cups at a time, and add the vanilla and almond extracts, beat again.
Taste the frosting to see if you want it sweeter. I liked the way mine turned out with 4 cups of powdered sugar. If the frosting is too thick add 1 tbsp of milk or heavy cream, beat until creamy.
1 Tbsp milk, or heavy cream works great too
Using a butter knife or spreader, spread the icing onto a rainbow cookie. Begin to add the Fruity Pebbles at the top of the cookie, beginning with red and going forward with orange, yellow, green, blue, and purple. Once all of the Fruity Pebbles are on the cookie, place shredded coconut where the clouds are. Repeat this process until all of the cookies are decorated. Store in an airtight container.