Make the pumpkin filling: In a medium saucepan, whisk together the pumpkin purée, 1½ cups of sugar, pumpkin spice, and cinnamon until fully combined. In a small bowl, stir together the cornstarch and apple juice until the cornstarch is completely dissolved — no lumps, please!
Cook the filling: Pour the apple juice mixture into the saucepan and whisk everything together. Cook over medium heat, bringing it to a gentle boil. Once it starts bubbling, lower the heat and let it simmer for about 10 minutes, stirring now and then so nothing sticks. Remove from heat and let the filling cool completely before assembling the cookies — it’ll thicken up as it cools.
Make the cookie dough: In a large mixing bowl, beat the melted butter and 1 cup of sugar together with a hand mixer until it thickens up a bit — about 2–3 minutes. Add in the molasses and egg, and beat again until smooth and well mixed.
Add the dry ingredients: Mix in the baking soda, cinnamon, pumpkin pie spice, salt, and flour. Keep mixing with the hand mixer until everything comes together in a soft dough. If it’s still sticky, add a little extra flour a tablespoon at a time until you can pinch it without it sticking to your fingers.
Chill and roll: Cover the dough and pop it in the fridge for 30 minutes. Once chilled, preheat your oven to 350°F. Lightly flour your surface and roll the dough out to about ¼ inch thick. Use a pumpkin-shaped cookie cutter (or just a round cutter or glass) to cut out the cookies. Flatten the top of the circle slightly to give it more of a pumpkin shape.
Create the pumpkin faces: You’ll need two pieces for each cookie: one for the base and one for the face. Take half of the cookie cutouts and use a small sharp knife to carefully cut triangle eyes and a mouth — just like a mini jack-o’-lantern!
Assemble the cookies: Spoon about 1 tablespoon of cooled pumpkin filling onto the center of each bottom cookie (the ones without faces). Then gently place a face cookie on top, lining it up as best you can. Lightly press the edges to seal them together — no need to be perfect, just make sure they’re closed.
Bake: Transfer the cookies to a parchment-lined baking sheet and bake for 10–13 minutes. Keep an eye on the center (especially around the nose/mouth area) to make sure it’s cooked through — that spot can bake a little slower. Let them cool on the baking sheet for a few minutes, then move to a cooling rack. Once cool, they’re ready to serve!