First, open paper bags and place one inside of the other. Pour Chex cereal into bags and set aside. Cover table or counter top with wax paper. Spray with non-stick cooking spray. Bring the first three ingredients to a boil on the stove in a large kettle, stir frequently as not to burn. When everything is all melted and incorporated, take off of heat and add vanilla and baking soda. Stir until foamy. Pour over the double bagged Chex. Roll down top and shake well. Microwave for 2 minutes and shake well. Microwave for 2 more minutes and shake again. Make sure to turn the bag on all sides each time you shake to spread the caramel. Open bag and check to make sure the caramel is spread evenly throughout the Chex. If not, shake it up again. However, you should be able to dump the Chex onto the sprayed wax paper. Gently spread the Chex into an even layer on waxed paper. Sprinkle with chocolate chips and nuts. Carefully stir mixture so that chocolate melts and lightly coats the cereal and the nuts mix in evenly. Stir every once in a while as it cools, so that it doesn’t dry in one huge clump.