Preheat oven to 350° F.
In a stand mixer (or by hand in a large bowl), combine vanilla cake mix, 1/2 cup melted butter, and 2 eggs. Mix until combined well. Place in refrigerator for 10 minutes.
In a stand mixer (or by hand in a large bowl), combine milk chocolate cake mix, 1/2 cup melted butter, and 2 eggs. Mix until combined well. Place in refrigerator for 10 minutes.
Scoop cookie dough onto sheet trays and bake for 10 minutes. Center should be slightly firm to the touch when done. Let cool on sheet tray for 2 minutes before transferring to cooling rack.
Repeat until vanilla and chocolate cookies are all baked. Cool completely.
To make filling, whisk together by hand or with a mixer the cream cheese, confectioner's sugar, and jam. Add one drop of food coloring then more if needed to created the classic bright pink color of neapolitan.
Add more confectioner's sugar to filling if needed to create desired consistency. Should be pretty thick so that it doesn't run out of the sides.
Add about 1 1/2 tablespoons of filling between one vanilla and one chocolate cookie. Makes about 24 sandwiches. Store cookies in the refrigerator. They also freeze great!