I love doing baking projects with my boys. It's the perfect combination of tactile play (mixing) and fine motor practice (measuring), finished off with a treat! My son's preschool has been exploring colors and rainbows, so I decided we should try making some rainbow sugar cookies. We both had a great time and the cookies were delicious, but I'm not sure I've completely tamed the inherent stickiness of a butter-based dough with this recipe. This was not entirely a bad thing since it was a chance for me to get my son to tolerate a sticky texture he'd normally resist--the promise of cookies at the end was good motivation! A shortening-based dough would be easier to work with, but if I'm putting in the effort of making cookies anyway, why not go for the good stuff?
Unless your kid is more coordinated than mine, you'll definitely want to gather and measure ingredients ahead of time. I like putting everything in little ramekins so we can read through the recipe together and easily add and mix.
First, cream the butter and sugar in a large bowl with a fork until light and fluffy, then add salt. This is my son's favorite part aside from cracking the eggs. (You could also do this in a mixer.)
Next, add the eggs. This never gets old, and my boys have been known to fight over who gets to crack the next one. You'll need to help pick out stray shell pieces, of course. Add the vanilla, then beat with a fork until combined (another good mixing step for young kids). Then dump the egg mixture into the butter and keep mixing with the fork until it's nice and smooth. Since you haven't added the flour yet, there's no danger of over-mixing, so feel free to keep on mixing as long as your kid is into it! Next, add the flour. My son likes to spoon the flour in a bit at a time, but just dumping it all in at once is fine, too. This is the step where you don't want to mix too much--just until the flour all combined.
Now the color! Divide the dough into 4 or 5 pieces, or as many colors as you'd like to make. The dough is so sticky that kneading it on the countertop is pretty messy and difficult, so I found the best method is to put each piece into a cereal bowl and mix it there. We had fun adding the food coloring just a drop at a time and watching the colors change. You can knead by hand or mix it with a fork. Don't worry if it's not perfectly combined, the cookies will still look nice. At this point my son was losing focus so I called for a break, which turned out to be a very good idea. The dough was getting very soft with all the mixing, so an hour or so in the fridge made it much easier to roll out into rainbows. To prevent it from drying out, wrap each color individually in plastic wrap. (You can leave it in the fridge for up to 2 days, or freeze it for up to a month.)
When you're ready to bake, preheat the oven to 375F and cover your baking sheet with parchment paper. (You can bake without it, but you run a much higher risk of the cookies sticking.) Take out the dough and dust your work surface with a little flour. To make a rainbow, pinch off four or five small pieces of dough in different colors. Roll each piece into a little snake and arrange into a rainbow shape directly on the parchment-covered cookie sheet. Lay each one down in an arch shape, one on top of the other, and then gently press together. Keep your cookies at least a half inch apart. When you have a sheet full, bake at 375F until edges are golden brown, about 6 to 8 minutes. You'll have better results if you bake them one sheet at a time. When cookies are done, immediately transfer them to a cooling rack. You can just slide the entire piece of parchment from the cookie sheet onto the rack. When cooled, these cookies can be stored in an airtight container for a couple weeks.