Preheat oven to 300 degrees. Spray a 9 x 13 pan with non-stick cooking spray and set aside.
Measure out 1 cup of cake mix and set aside.
In a large bowl, combine the remaining cake mix, 1 egg, and canola oil. Stir until moist and crumbly.
Press the mixture into the prepared 9 x 13 pan covering the bottom and ¾ up the sides of the pan.
In a mixing bowl, beat together cream cheese and sugar until fluffy. Then beat in the remaining 3 eggs one at a time. Add the reserved 1 cup of cake mix to the cream cheese mixure and beat for 1 minute
Once combined, slowly mix in the milk, lemon juice and vanilla to the cream cheese mixture until combined and smooth.
Pour the mixture into the prepared crust and bake at 300 degrees for 45-55 minutes until the center is set. It will still wiggle a little but will be more like set gelatin.
Allow cheesecake to cool completely and then refrigerate for at least 1 hour.
To serve, cut into squares and top with pie filling.