Preheat your oven to 350°F (175°C). In a large mixing bowl, beat together the softened cream cheese and unsalted butter using an electric mixer until the mixture is smooth and creamy. Add in the egg and vanilla extract, mixing until fully incorporated. Gradually blend in the yellow cake mix until you achieve a thick, cohesive dough.

Cover the bowl with plastic wrap and refrigerate it for at least 30 minutes. This helps firm up the dough.

Remove the dough from the fridge. Using a cookie scoop, take tablespoons of the dough and roll into uniform balls. Roll each ball in powdered sugar until fully coated. Place them on prepared baking sheets, ensuring 2 inches of space between each.

Slide the baking sheets into the preheated oven and bake for 10-12 minutes. They should have set edges but remain soft and gooey in the center.

After baking, let the cookies cool on the baking sheets for a few minutes before transferring them to wire racks to cool completely.