In a mixer or with a hand mixer, combine butter, peanut butter, 1 cup of white sugar, and brown sugar. Cream together for 2-3 minutes.
Add eggs and vanilla. Continue mixing until well combined, about 30-45 seconds.
Next, add salt and baking soda. Then mixing at a low speed, slowly add flour and oats a half cup at a time. Mix until well combined.
Add chocolate chips, M&Ms, Chocolate Chunks, and Reese's Cup pieces last. Mix until just combined. (I like to save a few of each type of chocolate to arrange on top once the dough is pressed in the pan to make it look pretty.)
The dough will be thick. Evenly distribute it by the spoonful onto a greased cookie sheet pan. In order to spread it evenly, you may need to spray your hand with cooking spray and press it down carefully until it is evenly distributed in the pan.
Once dough is evenly spread in the pan, sprinkle the top with 2 tbsp of granulated white sugar and decorate the top, if desired, with reserved pieces of chocolate and peanut butter cups.
Bake in a 350-degree oven for 18-22 minutes.
You do not want to overbake. The bars will be barely starting to brown on the edges. You can test the center with a toothpick if desired. Remember bars will continue to cook a little as they cool in the pan. In my oven, it takes exactly 19 minutes.
Let cool completely before cutting.
Enjoy
Recipe by Real Life Dinner at https://reallifedinner.com/loaded-peanut-butter-reeses-bars/