Preheat oven to 350 degrees. Line 2 cookie sheets with parchment paper.
In a medium bowl, sift together flour, cocoa powder, salt and baking powder. Set aside.
In the bowl of an electric mixer, beat the coconut oil until it is smooth. Add sugar and beat on medium speed for 2-3 minutes. Add in eggs and beat for 30 seconds more. Add vanilla and food coloring. Beat for another 3-60 seconds. Turn mixer to lowest setting. Slowly pour in the flour mixture and continue stirring until completely combined.
Scoop dough into small balls, the diameter of a quarter. Place onto prepared cookie sheets, about 2 inches apart. Bake 9-10 minutes until edges are set. Cool on cookie sheets for 1 minute, then move to wire rack to cool completely.
Once cookies are cool, mix the icing for the sandwiches.
For the icing
Put all ingredients into an electric mixer and beat on high speed until smooth and fluffy. Divide evenly between the cookies to make sandwiches. I used a piping back, but you can also just spoon the icing onto each cookie.
Store in an airtight container in the refrigerator. Serve at room temperature.