Place chow mein noodles and pretzels in a large Ziplock® bag and crush with a rolling pin into smaller pieces. About the size of the Rice Chex™ cereal. 

In a medium bowl, mix cereal, chow mein noodles, pretzels and M&M’s together and set aside.

In a medium saucepan, stir together brown sugar and corn syrup. Place saucepan over medium heat and bring to a boil  stirring constantly. Let sugar mixture boil for one minute then remove from the heat. Immediately add the peanut butter, vanilla, and salt. Stir until combined. Pour over the cereal mixture. 

Mix together until everything is completely coated and pour into a greased 13″ x 9″ pan. Gently press bars into shape until the pan is evenly covered.

|| Chocolate Topping || Melt chocolate chips and butter in a microwave or saucepan on the stovetop. Spread melted mixture evenly over the top of the bars. Sprinkle bars with peanut butter chips, chocolate shavings, etc. as desired. 

Let bars cool for at least 20 minutes before cutting.