Preheat oven to 350 degrees. In a large bowl blend together all the cake ingredients except for the eggs, flour and chocolate chips. Thoroughly blend the eggs in one at a time, then blend in the flour until completely incorporated into the batter.
Then gently stir in about 3/4 of the bag of mini chocolate chips. Pour the batter into a 9 x 13 an that has been sprayed with cooking spray.
In a medium size bowl blend together the cream cheese, sugar and vanilla. Spoon the mix into a sandwich bag and cut a small hole in one corner. Pipe the cream cheese mix all over the top of the cake batter, it doesn't need to be pretty and don't try to spread it out, it will even our while it bakes.
Combine the crumb topping ingredients in a medium size bowl with a pastry blender until all the ingredients are thoroughly blended together. Do not soften the butter. This takes a little work, but it's worth it.
Distribute the crumb topping all over the top but don't pat it down. Bake for about 40 minutes then check cake. If the center hasnt set up or if a toothpick comes out with wet cake batter you need to give it some more time. This can vary depending on your elevation.