Instructions

• Heat the oven to 350°F and line two baking sheets with parchment.
• Beat the softened butter and sugar until pale and fluffy. Beat in the egg and vanilla until smooth.
• Whisk the flour, funfetti cake mix, baking powder, and salt in a separate bowl. Add the dry mixture to the butter mixture and stir just until no dry streaks remain.
• Fold in the white chocolate chips and rainbow sprinkles without overmixing.
• Divide the dough into 12 portions, roll into balls, and place them several inches apart on the prepared sheets. Flatten each ball slightly.
• Bake for 10 to 12 minutes, until the edges are set and the centers still look slightly soft.
• Cool the cookies on the baking sheets for 10 minutes, then transfer them to a rack to cool completely.