Whisk together the flour, baking powder, baking soda, and salt. Set aside.

Using an electric mixer on medium speed, beat the butter and cream cheese until light and fluffy. Add the sugar and strawberries, and mix until combined. Mix in the egg and vanilla.

Reduce the mixer speed to low. Gradually add the flour mixture, mixing just until combined or a few small streaks of flour remain.

Stir in the M&Ms and white chocolate chips. If you like, reserve some of the add-ins for topping the portioned cookies before baking.

Cover and refrigerate the dough for 1 hour or up to overnight.

Using 2 tablespoons of dough at a time, roll the dough into balls and place on the prepared pans. Flatten each cookie slightly so that it's about 1/2-inch tall. If you reserved any add-ins for topping the cookies, add those now. You can also add sprinkles (jimmies or quins) if you like.

Bake, one pan at a time, 12 to 15 minutes, or until the cookies are lightly browned around the edges and appear set. (Keep the remaining dough refrigerated between baking batches.)

Place the pans on wire racks. If you want to add more sprinkles, add them now. After the cookies have cooled for 5 minutes, transfer them from the pan directly onto a wire rack to cool completely.