Preheat the oven to 350°F (convection). Line an 8×8-inch square pan with parchment paper and set aside.

In a medium bowl, mix together the room-temperature cream cheese, powdered sugar, vanilla extract, and marshmallow fluff until smooth and fully combined. Set aside.

In a large bowl or stand mixer fitted with the whisk or paddle attachment, beat the room-temperature butter, granulated sugar, and brown sugar until light and off-white in color, about 1–2 minutes.

Add in the egg, vanilla extract, and molasses, mixing until just combined.

Add the all-purpose flour, crushed graham crackers, baking powder, baking soda, and cinnamon to the bowl. Gently fold the dry ingredients into the dough until no dry spots remain.

Press about ⅔ of the cookie dough evenly into the prepared pan.

Spread the marshmallow cream cheese mixture over the dough in an even layer.

Fold the chocolate chunks or chips into the remaining cookie dough, then drop it over the marshmallow layer in chunks (it does not need to fully cover the surface).

Sprinkle with extra chocolate and graham cracker pieces, if desired.

Bake for 30–32 minutes, until the edges are set and lightly golden and the center is just set.

Allow the cookie bars to cool and chill for 45–60 minutes before slicing into 3×3 bars.

Enjoy fresh, or store the bars in an airtight container in the refrigerator for up to 8 days.