In a large bowl, sift together the flour, cake mix, salt, and baking soda.
Beat together the softened butter and both sugars until creamy and smooth. Add the egg and mix until fully combined. Then add vanilla extract.
Gradually add the flour mixture to the wet ingredients while mixing on low-medium speed until just combined. Fold in chocolate chips and sprinkles gently.
Cover the bowl tightly with plastic wrap and refrigerate the dough for at least two hours.
Preheat your oven to 350°F (177°C) and line two large cookie sheets with parchment paper.
Scoop rounded balls of cold dough onto an ungreased baking sheet, shaping them taller than wide.
Bake for about 13–15 minutes until edges are lightly browned while centers remain soft.
Cool on the baking sheet for five minutes before transferring to a wire rack to cool completely.