Cream together butter, cream cheese, and brown sugar. Slowly mix in the egg until fully incorporated.
Combine muffin mix, flour and cornstarch together and stir into the wet mixture
Add white chocolate chips and chill for 30 minutes.
Preheat oven to 325°F and line a cookie sheet with parchment paper.
Scoop cookie dough by tablespoon onto a lined cookie sheet and bake for 13-15 minutes.
Notes
*Use room temperature butter and cream cheese for easier mixing. *Scoop cookie dough with a cookie scoop for uniform size and even baking. *Allow cookies to sit on a baking sheet for 2 minutes before removing.