Heat Waffle Iron.
In a big mixing bowl combine the softened butter, sugar, eggs, cocoa, and vegetable oil. Mix together well.
Add in flour, salt, and vanilla. Mix all ingredient together until combined.
Drop batter by heaping tablespoon onto the generously greased waffle iron.
Keep the batter towards the center/middle of each quarter of the waffle iron. It will squish towards the outside edges when you close the lid.
Close the lid and cook for about 1 minute. You can open slightly to test for doneness. All waffle irons vary, so watch closely for the cook time that works best for you.
After they are done cooking, lift them off of the waffle iron with a fork and cool on a plate or cooling rack.
Be sure to spray the waffle iron in between each batch to prevent them from sticking.
While the cookies are cooling, make the frosting.
Mix the softened butter, powdered sugar, milk, vanilla, and cocoa until creamy and smooth.
Frost the cooled cookies and add sprinkles if desired.