<<Disclaimer: Verify this information before applying it to your situation.>>

I received several responses thanking me for posting the crumb topping
recipe,sayhing that they were tired on plain cakes and that this would
add an additional kick.

There is another thing to do with a plain cake.  Whichever one you sue,
spread a layer in the bottom of a cake pan [a tube pan or bundt pan
works really well], then add a layer of the streusel, then another layer
of batter and one more layer of struesel and end with batter.

Streusel

2 tabkesoons cocoa powder
2 tablelsppons sugar
1/4 cup chopped pecans [or walnuts, etc]
1 tablspoons cinnamon
1/2 teas nutmeg

blend and proceed as above.  If you make extra, it will keep in a
covered container.