For the whoopie pies, pre-heat oven to 160°C ((fan forced)) and line 2 baking trays with baking paper.
In a large bowl, sift together plain flour, baking powder and bi-carb soda. Then whisk in the almond flour until well combined.
In a small bowl, combine pumpkin spice ingredients. Add the spices to the flour mixture and whisk together.
In the bowl of an electric mixer, add the butter, sugar, treacle or golden syrup and beat until light and fluffy. Add eggs and beat together on medium speed for 2 minutes.
Add the flour mixture and beat on low until combined.
Place batter into a piping bag and snip 1cm off the end. Squeeze approx. 1 tablespoon of batter onto the tray, leaving 5cm between each whoopie to allow for spreading.
Bake one tray at a time for 13-15 minutes until golden in colour and just firm to the touch. Allow to cool on tray for 5-10 minutes then transfer to a wire rack to cool completely.
For the filling, in an electric mixer bowl, beat the butter until light and fluffy for approx. 5 minutes. Gradually beat in the icing sugar half a cup at a time until well combined. Beat in cocoa powder and chocolate spread until smooth and creamy.
To assemble, spoon the chocolate filling onto half of the whoopie pies and sandwich the remaining halves together. Add a row of mini marshmallows for the teeth. Use the larger marshmallows that have been cut into half for the eyes. Place a small blob of filling behind the eyes to secure them to the top of the whoopie pie. Add a choc chip for the pupil of the eyes.