Thick and Chewy M and M Cookie Bars

In my quest to use up my stockpile of baking supplies, I decided to use this recipe that I found on http://www.whatmegansmaking.com/. It lived up to its name thick, chewy and may I add; scrumptious. I took these squares to the Just Gutsa Crop along with some peanut butter cookies so if you're looking for the recipe, here it is...

Thick and Chewy M & M Cookie Bars

1 1/2 cups of butter or margarine(melted)
1 cup brown sugar
1/2 cup white sugar
2 tsp. vanilla
1 egg
1 egg yolk
2 1/8 cups flour
1/2 tsp salt
1/2 tsp baking soda
1 12 oz bag of M & M's ( I used milk chocolate )

Mix melted butter and sugars, stir in eggs and vanilla. Fold in dry ingredients being careful not to overmix. Fold in M & M's reserving a few to sprinkle on top. Turn batter into greased pan and spread out with a spatula. Sprinkle with M & M's. Bake at 350 for 30 min or until top is golden and firm and bars are starting to pull away from the edges. (I found I had to watch carefully as the middle was a little slower to firm up) Cool completely before cutting.