Preheat oven to 350 degrees. Line cookie sheets with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium speed until creamy, about 1 minutes. Add both sugars and corn syrup and beat on medium speed until light and fluffy, 2 to 3 minutes. Add the peanut butter and beat until well combined. Mix in the eggs and vanilla, beat on medium speed until smooth.
Add the salt and baking soda and mix until combined. Next add the oats and mix until combined. Add the potato chips and pretzels and mix on low speed until they are crushed into various-size pieces, about 1 minute.
Add the mini marshmallows and chocolate and butterscotch chips and mix on low speed until combined.
Scoop the dough into 1 1/2 oz balls (about 2 tablespoons) and place 7 dough balls on a cookie sheet. Use the bottom of a glass to flatten each ball of dough so it’s roughly 2 inches across. After flattening the dough, if any marshmallows are along the edges of the dough, pull them off and press them on top of the cookies (if they are on the edges when baking they will melt wonkily).
Bake the cookies (rotating halfway through) for 6 minutes, then give the pan a tap and then continue to bake for 2 to 3 minutes more, until the edges are light golden brown.
Transfer the pan to a wire rack and let the cookies cool completely on the pan. Store in an airtight container for up to 3 days.