The key to making homemade Oreos is the black cocoa powder. Look for it at specialty stores or Amazon. These have a deep rich chocolate-y flavor that will please all your little ghouls!
In a large bowl, sift together dry ingredients: flour, cocoa powders, salt and baking soda.
With a paddle attachment on an electric mixer, cream together the butter, sugar and vanilla until it is very light and fluffy.
Add the eggs one at a time and mix completely. Scrape the bowl down after each egg.
Carefully mix in the dry ingredients a 3rd at a time. Mix slowly until just combined.
Wrap in plastic wrap and refrigerate for at least 1/2 hour.
Prehead oven to 325F
Roll out dough out to 1/8 inch, cut with cookie cutters (flip 1/2 to create mirror images) and bake for 12-15 min.
Cool completely before adding filling.
With an electric mixer, cream butter until light and fluffy.
Slowly add confectioners sugar, one cup at a time. Scrape sides of bowl after each addition.
Mix in vanilla and slowly add milk 1 tablespoon at a time until you reach your desired consistency.
Pipe filling on one flat side of cookie. Leave 1/8 inch border.
With a matching black cookie, sandwich the 2 together. Refrigerate until ready to eat.