Preheat oven to 350F. In a large bowl, cream together butter, sugars, molasses and vanilla with an electric mixer. Beat in eggs until well blended. In a separate bowl, combine flour, oats, salt, baking soda and cinnamon. Combine dry ingredients with wet ingredients and raisins and mix by hand with a wooden spoon.
Drop dough by tablespoonfuls onto a well-greased baking sheet. The dough will be very tacky, so you may wish to moisten your fingers so it does not stick. With moistened fingers, press down on the dough and form it into circles about 1/8" thick. The circles should be about 2" diameter before baking. Bake for 8-10 minutes or until a couple of the cookies start to darken around the edges. They will still be very tender in the center until cool. Be careful not to overcook.
When cooled, the cookies should be about 1/4" thick and very soft and chewy. When cookies have completely cooled, assemble them by spreading about 1 1/2 tablespoons of marshmallow creme over the flat side of a cookie and then pressing another cookie on top, making a sandwich. Repeat for remaining cookies and filling. Store cookies wrapped in plastic wrap to keep them soft and chewy. They should be eaten within a day or two of filling.