Line a baking sheet with waxed paper.

Save 48 vanilla wafers for the buns. Place the rest in a plastic food storage bag and crush with a rolling pin until finely ground. Place in a mixing bowl with the sugar and salt, and stir to combine.

Combine the chocolate chips and milk in a microwave-safe bowl and microwave on high power for 45 seconds. Stir until smooth. Pour into the ground cookie mixture, stir until combined, and let cool 10 minutes. Roll the mixture into 24 (1-inch) balls, about 1 tablespoon per ball. Place on the wax paper-lined baking sheet. Flatten slightly to form into patties.

Combine the coconut, water, and green food coloring in a small plastic food storage bag and shake well to color the coconut.

Mix a few tablespoons of the white decorating icing with a few drops of yellow food coloring and mix until it looks like mustard. Place in a small plastic bag and snip off the tip.

Brush the rounded sides of 24 of the cookies with the melted butter and sprinkle with sesame seeds.

To assemble, place the 24 cookies without the sesame seeds on a serving platter, rounded side down. Top each cookie with one of the burger patties. Squeeze on a little of the yellow and red decorating icings to look like mustard and ketchup. Add a little green coconut on top and place the sesame seed cookies on top.

Can be made a day ahead and stored, covered with plastic wrap, in the refrigerator.