Place the dark brown sugar, light brown sugar, and butter into the bowl of a stand mixer fitted with the paddle attachment.

Cream the softened butter and sugars together on medium speed (speed 4 for a Kitchen Aid) for 5 minutes until light and fluffy.

Next, scrape down the sides of the bowl and add the molasses and vanilla extract. Mix on a medium speed until combined.

Then add one egg at a time; mixing until fully combined and scraping down the sides of the bowl after each egg.

In a separate bowl, whisk together the flour, salt, corn starch, baking soda, cinnamon, allspice, and ginger.

Add the dry ingredients to the mixing bowl and mix on a low speed until the flour is completely mixed in. Don’t overmix!

Using a cookie scoop, scoop the cookie dough, roll the cookie dough between the palm of your hands to make a smooth cookie dough ball and then slightly flatten the cookie dough ball (so its still puffy but flat on the top and bottom sides), roll the cookies in the granulated sugar, then place the cookie dough balls onto the parchment lined sheet trays.

Place the tray of cookies in the oven and bake for 10-12 minutes or until the edges are just set and the center should look a little soft.

Let the cookies cool completely before filling.

Place the softened butter in a mixing bowl and mix on a medium low speed until the butter is a pale-yellow color.

Add powdered sugar and start mixing at a low speed until all the powdered sugar is mixed in. Then mix on a medium high speed until the butter sugar mixture becomes white and fluffy.

Next, add vanilla and marshmallow fluff and mix on a medium high speed until combined.

Scrape down the sides of the bowl and add the heavy cream and pinch of salt. Mix on a medium-low speed until combined.

Next, spread or pipe the buttercream onto the backside of a cookie and sandwich together with another cookie. Enjoy!