In a mixing bowl whisk together funfetti cake mix, plain flour, baking soda and salt.
In the bowl of stand mixer beat butter , vanilla extract and sugars until light and fluffy, about 5 minutes. Add egg , mixing well until combined. Scrap sides as needed.
Add the flour mixture into butter. Mix until combined on low speed.
Mix in funfetti.
Preheat oven to 150 degrees celcius. Line a baking sheet with greaseproof paper. Roll 1 tablespoon (or small ice cream scoop) of dough into round balls. Place cookies 2 inches apart on baking sheet.
Bake dough for 10 -12 minutes, rotating half way through baking. The sides of cookies will look golden brown and centres soft.
Remove from oven. Leave to cool on baking sheet for 5 minutes before removing cookies. Place on wire rack to cool completely.