First, I made Dorie Greenspan's Chocolate Chocolate Cupcakes from pages 215-216 of Baking From My Home to Yours. Just Google them to find the recipe. It is everywhere. I may have over baked them, as they were kind of dry, but they had a yummy chocolate flavor.
After cooling the cupcakes, I then filled them with this recipe that I found on Baking Bites:
Vanilla Cream Filling
3 tbsp all purpose flour
1/2 cup milk (low fat is fine)
1/2 cup butter (or trans fat-free shortening)
1/2 cup granulated sugar
1/2 scraped vanilla bean or 1 tsp vanilla extract
Whisk together the flour and milk and cook in a small saucepan over medium heat until thick. This will only take a few minutes. Sir continuously to prevent the mixture from clumping and do not bring all the way to a boil. When thickened (consistency will be that of a thin pudding or custard), strain with a mesh strainer into a small bowl, cover with plastic wrap and let cool completely to room temperature.
When the milk mixture is cool, cream the butter (or shortening) and sugar together in a medium bowl until light. Add in the milk/flour mixture and the scraped vanilla bean seeds (or vanilla extract) and beat at high speed with an electric mixer for 7 minutes, until light and fluffy. Scrape into a pastry bag fitted with a plain tip, or a large ziplock bag with the corner cut off, and set aside until ready to fill your cupcakes.
In this case, I was afraid that it would not make enough icing, but it whipped up nicely. Also, I am not that good with the pastry bag, but every cupcake had filling. However, there was not enough left to make the Hostess squiggle. Next time, I would make 1.5 times the recipe.
After filling them, I glazed them with Dorie's recommended glaze. The glaze was much better at room temperature, than after I stored them in the fridge (I live in Texas, it gets hot here). After being in the fridge, the glaze was too hard for that true Hostess taste.