Spray a 6 quart crockpot with cooking spray then set aside.
Into a large bowl, place cake mix, eggs, buttermilk, butter, coffee, vanilla, and salt.
Beat until combined, then stir in 1/2 the chocolate chips.
Pour mixture into prepared crockpot.
In a medium sized bowl, place pudding mix and milk, then whisk together for 2 minutes, or until slightly thickened.
Pour into the crockpot over the cake batter - do not mix, then sprinkle remaining chocolate chips on top.
Cover the crockpot with a thin kitchen towel (be sure the towel doesn’t touch the top of the cake), then place the lid on top.
Cook on LOW 3-4 hours or HIGH 1 1/2 - 2 hours or until cake is cooked to your liking. The outside edges should be set, but the inside will be jiggly still - it’s a lava cake!