If you want a great chocolate cake recipe, I use the following. It has NEVER failed me. It keeps well, cuts cleanly and is easy to carve.
1 3/4 cup flour
2 cups sugar
3/4 cup cocoa powder
2 tsp baking soda
1 tsp baking powder
1/2 tsp salt
2 eggs
1 cup milk (or buttermilk)
1/2 cup soya bean oil
1 cup strong black coffee
1 tsp vanilla extract
Blend all ingredients in a food processor and bake in a greased and lined tin at 180°c (I’m in NZ. Just convert to farenhiet) for approx 1-1 1/2 hours.
When I’m making for kids, I usually omit the coffee and just add a cup of water or make it very weak. I have also make it gluten free, and you could make it dairy free by substituting almond milk etc.
Hope this helps. Good luck!