Make the Cookies

Preheat your oven to 350°F. Line two baking sheets with parchment paper.

Add the oats to a food processor and pulse a few times until they're broken into smaller pieces but not powdered.

In a medium bowl, whisk together the oats, flour, cinnamon, baking soda, and salt.

In a large mixing bowl, beat the browned butter, brown sugar, and granulated sugar until smooth and creamy.

Mix in the eggs one at a time, then add the molasses and vanilla.

Gradually add the dry ingredients and mix just until combined.

Scoop the dough into 2-tablespoon portions and place them 2 inches apart on the prepared baking sheets.

Bake for 10–12 minutes, or until the edges are lightly set and the centers still look slightly soft.

Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

Make the Filling

Beat the butter until light and fluffy.

Add the marshmallow creme, powdered sugar, vanilla, and salt. Beat until smooth and creamy.

Assemble

Spread or pipe the filling onto the flat side of one cooled cookie.

Top with another cookie and gently press together.

Repeat with the remaining cookies.