1(8 ounce or 12 ounce) package refrigerated crescent rolls (the bigger size makes it a little easier to wrap around the marshmallow)
Separate rolls into eight triangles. Combine sugar and cinnamon. Dip each marshmallow into butter, roll in cinnamon-sugar and place on a triangle. Pinch dough around marshmallow, sealing all edges. Make sure to seal well or all the marshmallow will escape.
Dip tops of dough into remaining butter and cinnamon-sugar. Place with sugar side up in greased muffin cups. It helps to use jumbo muffin tins so that the juice doesn't overflow.
Bake at 375 degrees for 10 to 15 minutes or until rolls are golden brown. Allow to cool slightly then eat warm.