Set the oven to 375°F and cover two large baking sheets with parchment. The parchment provides a clean surface for lifting the cookies after their initial cooling period.

Beat the cookie butter and both sugars at medium-high speed for about 2 minutes, using a paddle attachment or handheld mixer. Look for a paler, fluffy mixture with an evenly creamy texture.

Keep the same mixer speed while incorporating the egg, vanilla, and molasses, scraping the bowl as needed. The mixture should look uniform, without streaks of molasses or unmixed butter along the sides.

Combine the flour, baking soda, salt, cinnamon, cloves, ginger, nutmeg, and oats in a medium bowl with a whisk. Distributing the spices and leavener now prevents concentrated pockets in the finished dough.

Work the dry mixture into the butter mixture in two additions at low speed, then switch off the mixer and finish with a spatula. Stop when no dry patches remain so the dough stays tender rather than overworked.

Portion the dough with a 2-tablespoon scoop, leave 3 inches between portions, and bake for 10 minutes. A golden outer rim signals the intended doneness; avoid waiting for the centers to look hard or deeply browned.

Leave the baked cookies on their sheets for 5 minutes, then move them to a wire rack until completely cool. The brief sheet rest helps them firm up, and the rack releases lingering heat from underneath.

Continue baking the remaining dough by alternating sheets that have cooled completely. A cool sheet helps each batch spread consistently instead of melting the dough’s butter before baking begins.

Whip the filling butter at high speed for about 1 minute. It should become creamy and lighter in texture, with no firm lumps remaining.

Beat in the powdered sugar at medium speed for 1–2 minutes. The mixture should become evenly combined before the liquid ingredients go in.

Add the heavy whipping cream, vanilla, salt, and pumpkin spice spread, then beat until uniform. The finished buttercream should look smooth and fluffy, without streaks of pumpkin spread.

Spread 1.5 tablespoons of filling onto the flat undersides of half the cooled cookies, then cap them with the remaining cookies facing right side up. A gentle press should secure each sandwich without pushing the filling beyond its edges.

Place the finished sandwiches in a covered container and refrigerate for cautious storage. Keeping the filling cool also helps it hold its shape, especially in a warm kitchen.