Preheat oven to 350 degrees. Line a 9x13" rectangular pan with foil, extending the sides of the foil over the edges of the pan. Spray the foil liberally with cooking spray; set aside.

In a large bowl, combine the cake mix, egg, melted butter, and lemon zest together until a soft dough forms. Press the dough evenly into the baking pan and set aside briefly.

In the bowl of a stand mixer, beat the cream cheese until smooth, about 1 minute. Beat in the eggs, one at a time, beating well after each addition, followed by the raspberry gelatin and the freeze-dried raspberry powder. Beat in the confectioners' sugar until well blended, and lastly, beat in the melted butter and lemon juice. Mixture should be smooth.

Pour the mixture evenly over the lemon cake base in the pan and bake for approx. 37-45 minutes or until the center is just about set (if it jiggles slightly, that's okay - the mixture will continue to cook as it cools down). Bring to room temperature, then refrigerate for at least 2 hours before cutting into squares.