I've not tried this recipe, but it looks good on paper...
Chocolate Cream Puff Dough:
Prepare dough as above, only add 1 tablespoon sugar to the milk and 2 tablespoons cocoa powder to the flour.
Chocolate Pastry Filling:
2 cups milk
6 egg yolks
1/2 cup sugar
1/2 cup all-purpose flour
5 oz. unsweetened chocolate, chopped into small pieces
1/2 cup heavy cream
Bring milk to boil in a small pan. In a bowl, heat the yolks and sugar until pale and thick. Stir in the flour. Slowly pour about 1 cup of the hot milk into the yolks, stirring constantly. Return the yolk mixture to the remaining milk in the pan and cook, stirring until the sauce boils for 1 minute. Remove from the heat and stir in the chocolate until smooth. Strain into a bowl and cover closely with plastic wrap. Cool to room temperature. In a bowl, whip the heavy cream until stiff. Fold into the cooled pastry cream, and then fill the cream puffs.
Top with chocolate frosting, eat, and then nurse your bellyache.