01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper or grease lightly.
02 - Combine cake mix, melted butter, and egg in a mixing bowl. Mix until soft dough forms.
03 - Press dough evenly into the bottom of the prepared pan.
04 - Beat cream cheese until smooth. Add eggs one at a time, then mix in powdered sugar, lemon juice, lemon zest, and vanilla extract until fluffy and smooth.
05 - Pour lemon mixture over the base and spread evenly. Bake for 35–40 minutes until edges are set and center is slightly jiggly.
06 - Let cool completely before cutting into squares. Dust with additional powdered sugar if desired.