Cream the butter and sugar together with a hand held mixer or stand up mixer until light and fluffy.  Mix in the egg and vanilla until just combined.

In a separate bowl, whisk together the flour, baking soda and salt.  Gradually add the dry ingredients into the wet ingredients until just combined.  Be careful not to over mix the batter.

Then fold in the white chocolate chips and Marshmallows (reserving some for the tops).  Do not overman or the marshmallows may break down.

Chill the dough for at least 30 minutes but for no more than 1 hour (or the marshmallows in the dough could break down).

Preheat the oven to 350 degrees F and use a cookie scoop to place the cookie dough on baking sheets approximately 2-3 inches apart and top the cookies with the reserved marshmallows (4-5 per cookie).  Bake the cookies for 8-10 minutes until the cookies are slightly golden brown around the edges (note: they may look slightly raw in the center).

Allow the cookies to sit on the baking sheet for 5 minutes.  Then move them to wire racks to cool completely.

Then the cookies are ready to serve and enjoy!