Heat oven to 350 degrees and spray a 9x13 baking dish or line with parchment paper.

In large bowl, mix together oats, flour, brown sugar, pecans, salt, and melted butter. Stir together until combined and crumbly. Remove 1 cup and reserve for later. Press remaining into baking pan.

In saucepan over medium heat, stir the condensed milk, 2 tablespoons butter, and 1 cup semi-sweet chocolate chips until smooth and melted. Pour over the crust in pan. Sprinkle with the reserved mix and the m&m's. Press down lightly.

Bake for 25 minutes. They will look like they're not done, but will set up very nicely after they cool.

Let cool for 1-2 hours before cutting. Store leftovers covered at room temperature.