Preheat the oven to 350 degrees
Whisk flour and baking soda together in a small bowl. Set aside.
Cream together the butter and sugars in a large bowl, with a hand mixer. Add in the pudding mix, mix again. Add the eggs and vanilla mix again, scrape the sides of the bowl. Slowly add in the flour and baking soda mixture, just until combined. Add in the chocolate chips and mini marshmallows, stir by hand.
Using a large spoon or cookie scoop, drop dough on a greased cookie sheet, or a cookie sheet lined with a silicone baking mat.
Bake for 8-10 minutes. Let cool for a minute to set, and place cookies on a wire rack to cool.