Make the paper houses: Print out the stencil (see link above) and trace it 24 times on Bristol board. Draw folding lines onto each house and cut out the houses. Gently fold along the folding lines, then draw your desired pattern onto the houses (on the opposite side of the folding lines), making sure to include a number from 1-24. To build the houses, stick some tape or glue (tape works best!) onto the tabs and tape the houses together from the inside, leaving the roofs open. Set aside and make the truffles.
To make the truffles: In a small bowl, combine the cinnamon, ginger, cloves and nutmeg. Measure 3 teaspoons of gingerbread spice mix and add to the hot cream, dissolving completely. Add the cream and salt to the melted dark chocolate and stir until fully combined. Place in the fridge until chilled and thickened, 1-2 hours. Beat the ganache with an electric mixer until it lightens in colour and thickens to piping consistency. Place in a piping bag fitted with a large, round tip. Pour some melted milk chocolate into a chocolate mold of your choice and spread onto the inside of the mold to cover all walls. Place in the freezer to stiffen, about 5-10 minutes. Fill the chocolates with the ganache filling, then top with more melted chocolate. Return to the freezer to stiffen, 10-20 minutes. Unmold, then wrap in aluminum foil. Place 1 chocolate in each house and tape the roofs shut. These chocolates are best stored in the fridge, unless you are tempering the chocolate, as tempered chocolate is best kept at room temperature.