Mix dry ingredients (flour, sugar, cocoa, salt, baking soda) and then add water, oil, vinegar and vanilla. Mix well.
Put cupcake papers in a muffin tin and fill 1/2 full with the batter.
Cream together cream cheese, egg, sugar, and salt, and stir in chocolate.
Put a spoonful of filling into center of each cup of batter.
Bake at 350F / 180C for about 25 minutes.
While cupcakes are baking, whip up the frosting. In a medium bowl, cream together the cream cheese and butter until creamy. Mix in the vanilla, then gradually stir in the confectioners' sugar. Frost the cupcakes after they've had time to fully cool.
Makes about 32 cupcakes.
Contributed by Katie Hanson, Davenport, IA from a 1960s church cookbook in North Dakota