Cook ¼ cup oats and raisins in milk/water mixture.
Process remaining 1 cup oats with dry ingredients.
Cream butter, oil, brown sugar, molasses, egg, and vanilla.
Add dry ingredients to wet ingredients and mix to form dough.
Scoop dough onto baking sheet and bake at 350°F.
Make marshmallow filling by softening gelatin in ice water, then cooking sugar, corn syrup, and egg whites.
Whip the marshmallow mixture until thick and fluffy.
Assemble the cookies by placing a dollop of marshmallow filling between two cookies.
