Preheat the oven to 350 degrees. Lay out butter to soften for frosting.
Cream butter and sugar for the cookies.
Add egg and vanilla. And continue to mix.
In a separate bowl add flour, baking soda, and salt.
Add in the flour mixture to the butter mixture. Mix.
Add in chocolate chips.
Scoop a full tablespoon out for each cookie on a cookie sheet.
Cook at 350 for about 12 minutes.
While cookies are baking, cream butter for several minutes for frosting.
Add in powdered sugar, vanilla, and milk. Blend
Once cookies are completely cooled scoop out about a tablespoon of frosting and place on a cookie. Put another cookie on top and press down, gently moving the top cookie in a circle to move frosting evenly.
Pour out mini chocolate chips onto a plate.
Roll the sides of the sandwich cookie in mini chocolate chip cookie sandwich.
Store in an airtight container.