Apparently, attempting to make the sponge cake, cream-filled goodies has been an ongoing project for many. There was an Epic 2010 Homemade Twinkie Challenge where judges selected the best recipes for the cake and the filling.
Others then took those two best recipes and put them together.
The ingredients needed for 12 full-sized or 24 mini Twinkies are:
16-ounce box golden pound cake mix
4 egg whites, beaten until stiff
2/3 cup water
1/4 cup non-hydrogenated shortening or coconut oil
1/4 cup margarine
1 cup powdered sugar
1 tsp. vanilla extract
Twinkie Molds or aluminum foil
Non-stick cooking spray
A marinade injector
Some pre-planning work is necessary. To make molds from aluminum foil, you can cut 24 nine-inch foil sheets or you can buy a box of foil sheets from any grocery store or supermarket. They should be about the right size, although you will want to look on the box for the size and you may have to cut the sheets down to the correct size
Fold each piece of aluminum foil in half twice. Then wrap the folded foil around a small spice bottle to create a mold.
Leave the top of the mold open to pour in the batter
Preheat the over to 325 degrees. Arrange the molds on a cookie sheet or in a shallow pan. Spray them with a non-stick cooking spray.
Now you are ready to make the cake. Whip egg whites on a high speed until they stiffen. Add the cake mix and water and beat on a medium speed until mixed. That should take about two minutes.
Pour the batter evenly in each of the molds. Bake at 325 for about 20 minutes. The cakes will spring back when touched when they are done. Another method is to insert a toothpick into the center. The cakes are done when the toothpick comes out clean and the cakes are golden brown.
Let the cakes cook outside the oven for about five minutes. Take a knife and run along the edge of the molds to loosen them. Turn each mold over onto a rack, remove the cakes and let them cool.
To make the filling, beat the shortening and margarine together in a mixer. Mix on a medium speed until creamy. Add powdered sugar and beat on a medium speed until light and fluffy, which should take about five minutes.
Add the vanilla and continue mixing for another two minutes.
After the cakes have cooled, flip them over and use a marinade injector to inject cream into two incisions running the length of a mini cake or three incisions running the length of full-sized Twinkies.
Leftovers should be stored in an air-tight container.