Pour the melted butter over the chocolate and stir to combine, then pour in the Baileys Pumpkin Spice and stir again. Set aside to cool slightly.
Whisk the eggs until they foam up and then add the sugar and keep whisking for a minute or so. Pour in the cooled chocolate mixture and stir together then sift in all the dry ingredients and fold everything through.
Pour the mixture into a lined 23cm squared baking tray and smooth out.
Bake for 20-25 mins (until the middle wobbles slightly - but not too much) then leave to cool in their tin for at least 3 hours.
When the brownies have completely cooled cut them into 16 squares and top with a marshmallow and drizzle with molten white chocolate. Finally, stick two chocolate chips on each for eyes!