In a big bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Add sugar, baking soda, and salt. Beat until combined, scraping bowl occasionally. Beat in egg and vanilla until combined. Alternately add flour and buttermilk, beating on low speed after each addition just until mixture is combined. I used my medium sized cookie scoop to get perfectly measured balls of batter onto the sheet about an inch and a half apart. 

Bake for about 10 minutes or until you see the edge getting golden and you can touch the tops. Cool completely on the paper on a wire rack. I peeled most of the cooled cookies off the paper, but used a cake server to free the stubborn ones. 

Microwave your mini mallows about 15-20 seconds until they are a fluffy melty liquid substance, add a splash of milk, and stir!

Spread the flat side of half of the cookies with enough of the melted mixture to make you happy. I just poured it on straight from my bowl. I will warn you - this part is super messy! I got drips of melty marshmallows all over everything!

Enjoy! You can freeze these for up to a month or keep them in the fridge for a couple days. they are best served slightly chilled! 

I also made some that were pink! Same ingredients, just swap the hot chocolate mix for a couple drops of red food coloring. The filling for the pink pies was made by mixing marscapone and seedless raspberry preserves. YUM! Heavenly.

:)