Preheat the oven to 325°Line two baking sheets with parchment paper.
In a small bowl, whisk together the dry ingredients (flour, baking soda, salt, & tapioca starch). Set aside.
With an electric mixer, cream together the butter and sugars. (About 2 min on medium speed.)
Mix in the egg and vanilla.
Add in the dry ingredients and mix until just combined.
Stir in the unicorn chips and sprinkles.
Scoop 1 tablespoon-size portions of dough and place 2-inches apart on cookie sheets. Bake 12-14 minutes until the edges are lightly golden and centers are just starting to brown. (Do not overbake… unless you like a crispier cookie!)