In the bowl of a stand mixer using a paddle attachment, or in a large bowl using an hand mixer, cream together the butter and sugars until pale, light, and fluffy.
Add in the vanilla, egg, and peanut butter and beat until combined, scraping down the bowl as needed.
Sift the baking soda, salt, and flour into the bowl and beat to combine.
Add in the oats and mix thoroughly.
Crumble the pretzels, then stir in along with the M&Ms and chocolate chips.
Use a large cookie scoop (or roll into 2 tbsp balls) to scoop dough onto the prepared sheet.
Bake 10-15 minutes until golden brown.
Remove from oven and press candy eyeballs into the cooked cookie while still warm.
Cool 5 minutes on sheet, then remove to wire rack to fully cool.