For a recent Beehive Class Activity, we learned to make no-bake cookies.
Ever competitive, the Beehive Class Presidency thought it would be fun to make it a competition. We selected 3 different types of no-bake cookie recipes and purchased the ingredients ahead of time. We also printed the recipes so that each team would have a copy of the recipe they were working on.
We did 3 teams (2 girls on a team), but if you have a larger class you could either have more teams or more girls per team.
We made Peanut-Butter No-Bake Cookies (recipe HERE), Nutella No-Bake Cookies (recipe HERE), and traditional No-Bake Cookies (recipe HERE)
I thought for sure that the Nutella cookies (a big favorite among some of our YW) would be the winner, but everyone liked the Peanut-Butter and traditional versions of the cookies best.
I would recommend making the cookies at the beginning of your activity and refrigerating them so that they "set" - then you can play a game or something and eat/judge the cookies at the end!
This was a relatively low-cost activity, since rolled oats, sugar, etc are fairly low in price and you don't use much of the more expensive ingredients (peanut butter, nutella, etc). A bonus is that the refreshments are part of the activity! And if you are careful with the ingredients, these cookies can be gluten-free, if that is a concern for any of your girls (there is no flour in these recipes, but check the label