16-ounce box golden pound cake mix
4 egg whites, beaten until stiff
2/3 cup (160mL) water
1/4 cup (57g) non-hydrogenated shortening or coconut oil
1/4 cup (57g) margarine
1 cup (125g) powdered sugar
1 tsp. vanilla extract
Twinkie Molds (aluminum foil will do in a pinch)
Non-stick cooking spray
Preheat the oven to 325F (160C)
Whip egg whites on high until stiff.
Add cake mix and water, and beat on medium speed until completely blended, about 2 minutes.
Divide batter evenly among the baking pan wells and bake at 325F (160C) until cakes spring back when touched, a toothpick inserted into the center comes out clean, and cakes are golden brown, about 20 to 22 minutes.
Remove from the oven and let cool for 5 minutes; then loosen from the sides by running a knife along the edge of the pan. Invert onto a rack, remove cakes, and cool completely.
Beat together the shortening and margarine with mixer until well combined and creamy.
Add the powdered sugar and beat until completely light and fluffy, about 5 minutes.
Add the vanilla and beat for another 2 minutes.
Once cakes are cool, flip each over, and with a straw or a skewer, make two incisions running the length of the cake (three for full sized Twinkies).
Scoop filling into a pastry bag fitted with a medium-size plain tip (or snip the corner off of a small plastic bag).
Place the tip into each incision, and press cream into the incisions until full. When cakes are completely full, turn them back over and serve.
Store any leftovers in an airtight container.