Melt butter in a medium saucepan and tip in both the sugars, stir well until well mixed.
Take off heat and whisk in the egg
Next tip in the flour, oats, salt and vanilla and mix well with a wooden spoon or spatula.
Refrigerate the cookie dough mixture for about ½ an hour until it is malleable and easy to handle.
Once the mixture is cold, take golf ball sized pieces of the dough in your slightly floured hand and roll into a ball, then flatten in your hand and transfer to a lined baking sheet. Repeat until the dough finishes
Bake for 10-12 minutes in a preheated oven 180 C (350 F). They will initially be slightly soft to the touch but harden up as they cool down
Take your favorite store bought ice cream, soften it slightly, and plop 2 tablespoons on each cookie base. Cover it with another cookie, wrap in cling and stick it in the freezer for 10 minutes. Repeat until all your sandwiches are done.
Put crushed Oreo cookies on a tray, wheel around your cold sandwich cookies around so that they are covered by the black powdered goodness and put them back in the freezer.
Freeze for a minimum of three hours and then they will be ready to impress and devour.