Place the butter, cream cheese, vanilla and salt in the bowl of a stand mixer, or a large bowl if using a hand mixer.
Beat on medium until smooth and combined.
Sift the powdered sugar into the bowl and beat until incorporated and the frosting is smooth.
Divide the frosting in half. Add a few drops of the food coloring to one portion.
Place a decorating tip with a round 1/4" oping in a large pastry bag.
Lay a piece of plastic wrap flat on your counter.
Place a line of the red frosting down thw middle of the plastic wrap. Place a line of the white frosting next to the red.
Roll the plastic wrap to make a tube of frosting and twist the ends.
Cut off one end to expose the buttercream and place it into the pastry bag. Squeeze thebag so that the buttercream goes down to the tip.
To decorate the cookies, start in the middle and pipe a continuous circle to about 1/2" from the edge of the cookie. Sprinkle with additional vanilla sandwich cookie crumbs.
Enjoy!