Lightly spray the inside of a 6-quart oval slow cooker with non-stick cooking spray.
In a large bowl whisk eggs, sour cream and water. Add cake mix, flour and sugar until just combined. Stir in mini-marshmallows.
Pour into prepared slow cooker, cover and cook on low for 3 to 4 hours or until the internal temperature reaches 165ºF. Cake should be wet in the centre, DO NOT OVER COOK.
Drop spoonfuls of marshmallow creme evenly over the surface of the cake – it will spread as it stands. Sprinkle with chocolate chips.
Remove the crockery liner to the countertop. Cover and let stand for 15-20 minutes. Remove lid and sprinkle with broken graham pieces. Serve alone or with a scoop of vanilla ice cream.