Prepare the Crust

1. Preheat Oven: Preheat the oven to 350°F (175°C). Grease a 9×13-inch baking pan.
2. Mix Crust Ingredients: In a large bowl, combine the yellow cake mix, melted butter, and egg. Mix until a dough forms.
3. Press Into Pan: Press the dough evenly into the bottom of the prepared baking pan to form the crust.

Make the Filling

1. Beat Cream Cheese: In a separate bowl, beat the softened cream cheese until smooth.
2. Add Eggs and Flavorings: Add the eggs, lemon juice, lemon zest, and vanilla extract. Beat until well combined.
3. Incorporate Powdered Sugar: Gradually add the powdered sugar, mixing until the filling is smooth.
4. Fold in Coconut: Gently fold in the shredded coconut.

Assemble and Bake

1. Pour Filling Over Crust: Spread the cream cheese mixture evenly over the crust in the baking pan.
2. Bake: Bake in the preheated oven for 30-35 minutes, or until the edges are golden and the center is set but still slightly gooey.
3. Cool Completely: Allow the bars to cool in the pan before cutting into squares.