Preheat oven to 375°F. Line 2 large baking sheets with parchment paper and set aside.
In a large mixing bowl, use a hand mixer to cream the butter and sugars together at medium speed until light and creamy, about 2 minutes.
1 cup unsalted butter, ¾ cup brown sugar, ¼ cup granulated sugar
Add the eggs, molasses, and vanilla and mix well.
2 large eggs, 2 tablespoons unsulphured molasses, 1 teaspoon pure vanilla extract
In another bowl, whisk the oats, flour, baking soda, cinnamon, salt, and cloves together.
2½ cups quick-cooking oats, 2 cups all-purpose flour, 1 teaspoon baking soda, 1 teaspoon ground cinnamon, ½ teaspoon kosher salt, ⅛ teaspoon ground cloves
Add the dry ingredients to the wet ingredients, mixing until just combined.
Scoop 2-tablespoon-sized cookies onto the prepared baking sheets – place them 3 inches apart.
Bake for 8-10 minutes, until lightly golden around the edges.
Remove the baking sheet from the oven and tap it gently 3-4 times on the counter to flatten the cookies. Allow the cookies to cool for at least 5 minutes. Transfer to a cooling rack to cool completely.
While the cookies cool, make the filling. Place all of the filling ingredients in a clean bowl and use a hand mixer to combine until smooth.
1 cup powdered sugar, 1 tablespoon heavy cream, 1 teaspoon pure vanilla extract, 1 cup marshmallow fluff, ½ cup unsalted butter
Use a knife or icing spatula to spread about 2 tablespoons of filling on the bottom side of half of the cookies, then sandwich each with a second cookie. Serve and enjoy!