Add the oatmeal to a food processor and pulse several times until the oatmeal is broken down into small pieces but not ground into powder.

Add the flour, cinnamon, baking soda and salt to the same bowl and pulse until the dry ingredients are fully combined.

Add the softened butter, brown sugar and granulated sugar to a mixing bowl.

Use the beater attachment for a hand mixer or stand mixer and cream together until smooth and combined.

Add the eggs, molasses and vanilla to the same bowl and beat until fully incorporated, scraping the bowl down as needed.

Add the dry ingredients to the mixing bowl and cream together until fully incorporated.

Cover and chill the dough for 15 minutes.

Preheat the oven to 350 degrees.

Prepare 2 large baking sheets with parchment paper.

Use a 1 ½ Tablespoon cookie scoop to measure out each cookie ball. Place them on the prepared cookie sheet 2-3 inches apart.

Bake for 8-10 minutes or until the edges of the cookies are JUST starting to set around the edges, but most of the rest of the cookie will still be underdone. (As they chill, they will firm up.)

Remove the cookies and allow them to cool before removing from the baking sheet.

In a clean mixing bowl, add the butter and cream using a paddle attachment until smooth.

Add the marshmallow crème and cream until combined.

Add the powdered sugar a little at a time and mix until fully incorporated.

Add the vanilla and salt and cream again until all ingredients are combined, and the filling is smooth.

Add the frosting to a piping bag that has a large round tip.

Squeeze on enough frosting so that when you add the second cookie and gently press together, you are left with ½ inch of filling exposed.