I've never tasted a Twinkie, but figured out that with the right filling and cake,
I could make one hell of a Twinkie wannabe.
I've made a cake out of Pillsbury vanilla cake mix and filled
them with Marshmallow cream I've prepared.
Pillsbury vanilla cake mix
Twinkie muffin tins/English cake pans
For the Marshmallow cream:
3 egg whites
2 cups marshmallow
Tsp.  vanilla extract
1/4 cup sugar
for the coating:
Dark chocolate
(Measurements were made with 200ml cup)
Prepare the cake according to the instructions.
Let the cake cool and meanwhile prepare the Marshmallow cream:
Boil water in a saucepan and like in Bain Marie, put another pot over the saucepan and beat the 3 egg whites for about 3 minutes. Add the Marshmallows and continue beating for another 3-4 minutes.
Take off from the heat and add the vanilla extract and sugar and beat well.
Transfer into a piping bag and pipe from the bottom side of the Twinkies. 
You can melt dark chocolate and coat the Twinkies as you desire.
If you left with extra marshmallow cream, you can spread on top of a biscuit and drizzle some melted chocolate and you have yourself a s'mores.