In a medium bowl, whisk together the flour, baking soda, and salt.

1. In a large bowl, cream the butter, granulated sugar, and brown sugar until light and fluffy.
2. Add eggs and vanilla extract to the butter mixture and mix well.
3. Gradually add the dry ingredients to the wet ingredients, mixing until combined.
4. Fold in the rainbow sprinkles.
5. Scoop dough onto a lined baking sheet and bake at 350°F (175°C) for 10–12 minutes until the edges are golden.
6. Let cookies cool completely on a wire rack.
7. In a bowl, whisk together heavy cream, whole milk, sugar, vanilla extract, and dry yellow cake mix until fully combined.
8. Churn the mixture in an ice cream maker according to the manufacturer’s instructions.
9. In the last few minutes of churning, add in the rainbow sprinkles.
10. Once churned, freeze the ice cream until firm, about 2 hours.
11. To assemble, scoop ice cream onto the flat side of a cookie and top with another cookie to make a sandwich.
12. Press gently and place sandwiches in the freezer for at least 1–2 hours to set.