Heat oven to 350 degrees.

1. In a stand mixer, cream together shortening and sugar.
    
2. Once fully combined, add in eggs, one at a time on medium low speed.
3. Turn mixer to low and add in vanilla, buttermilk and food coloring. In a separate bowl, whisk together flour, cocoa and salt.
4. With mixer on low, add dry ingredients into the wet ingredients.
5. You may need to add more buttermilk if your dough is still a bit dry. (You may add up to 1/4 cup more if needed. Do not add more than 1/4 cup.)
6. Using very small amounts, place dough into a piping bag fitted with a 1M (or 2D) tip. Pipe out individual rosettes onto a parchment lined baking sheet.
7. Bake for 6-8 minutes. Dough will still appear to be a bit "wet" looking when the cookies are done, and this is ok. Allow cookie to cool to room temperature.
8. To make cookie sandwich's, place about 1 tbsp marshmallow buttercream on bottom of cookie, then place another cookie on top and press gently.