A “recipe cloner” Todd Wilber reverse-engineers specific foods ingredient by ingredient, until he creates a recipe that recreates the original.  Here's his recipe for the Twinkie filling.  

Ingredients

Marshmallow filling

  • 1/4 Teaspoon salt
  • 2 Cup (one 7-ounce jar) marshmallow creme
  • 1/4 Teaspoon salt
  • 1/2 Cup shortening
  • 1/3 Cup powdered sugar
  • 1/2 Teaspoon vanilla

Preparation

Step 1:

Combine salt with hot water in a small bowl and stir until salt is dissolved. Let cool.

Step 2:

Combine the marshmallow creme, shortening, powdered sugar, and vanilla in a medium bowl and beat until fluffy, using an electric mixer on high speed.

Step 3:

Add salt water and beat to combine.

Step 4:

When the cakes are cool, use a skewer or a chopstick to make three holes along the bottom, moving the stick around slightly to create space inside the cake. Fit a pastry bag with a small tip and fill it with the marshmallow creme mixture (or scoop it into a resealable bag and snip off a tiny bit of one corner; pipe filling into each cake, using the three holes.