In a large mixing bowl, combine the dry ingredients. Add the eggs, water, oil, vinegar and vanilla; mix well. Pour into 18 greased or paper-lined muffin cups.
For filling, beat cream cheese and sugar in another mixing bowl. Add egg and salt; mix well. Fold in chocolate chips. Drop by tablespoonfuls into center of each cupcake. Put a dollop of chocolate batter on top then sprinkle with nuts. Bake at 350 degrees F for 25-30 minutes.