1. Preheat your oven to 325 degrees.
2. Place 1 1/2 C butter into a large glass bowl. Melt the butter in the microwave.
3. Add 2 C brown sugar and 1 C white sugar and stir to combine. Then add 2 eggs, 2 egg yolks and 4 tsp vanilla. Whisk it together until well combined.
4. In a separate bowl combine 4 1/4 C flour, 1 tsp salt and 1 tsp baking soda.
5. Stir the dry mixture into the sugar mixture. Don''t mix it in all the way. The trick to making these bars nice and soft on the inside is not to over mix and not to over bake. So, at this stage...leave a bit of the flour showing. It will incorporate nicely for you as you stir in the chocolate.
6. Add 2 C milk chocolate chips and 2 C of M and M''s (almost all of a medium sized bag). You can use any kind of chocolate chips.
7. Stir the chocolate in to combine.
8. Spray a large cookie sheet with cooking spray (mine is 12 x 17). Press the dough evenly into the pan.
9. Bake for 22-25 minutes or until the outside is slightly golden. You want to be sure not to over bake. They are much better if the inside is nice and soft.
10. Allow them to cool for about 10 minutes then slice into bars and enjoy!
