Preheat oven to 300 degrees F. Measure out
Stir together remaining dry cake mix, 1 egg, flour and oil in a large bowl. Press this crumb mixture evenly into bottom and three-quarters of the way up the sides of a 13 x 9 x 2-inch pan.
In the same bowl, blend sour cream, sugar, 2 eggs, reserved cake mix, and lemon juice for 1 minute at low speed. Gradually add milk and food coloring while beating for 2 minutes at medium speed. Pour into crumb crust. Bake at 300 degrees F for 45 to 50 minutes, or until center is firm. Do not overbake. Cool at room temperature for 1 hour.
Top with blueberry pie filling or your favorite pie filling and refrigerate.
Source: E-Cookbooks.net