Baking Steps

• In a large bowl, whisk together the flour, baking soda, salt, cinnamon, pumpkin pie spice, and oats until well combined. Set aside.
• Beat the butter, brown sugar, and white sugar together until creamy and light in color, about 2 minutes.
• Mix in the vanilla, molasses, and eggs until fully combined, about 1 minute.
• Gradually incorporate the dry ingredients into the wet mixture, mixing on low speed until just combined.
• Chill the dough in the refrigerator for 15 minutes while preheating the oven to 350°F (175°C).
• Scoop the dough into approximately 36 balls and place on prepared baking sheets.
• Bake for 8–9 minutes until just set, then cool on a wire rack.
• Beat together the butter and marshmallow fluff until light and airy, about 3 minutes.
• Add sifted powdered sugar, vanilla, and salt, mix until combined, then beat until fluffy.
• Spread frosting on the flat side of half the cookies, then sandwich with the remaining cookies.
• Chill the assembled pies in the freezer for at least 10 minutes before serving.