Heat the honey, treacle and butter in a pan until the butter melts. Sift the flour, bicarbonate of soda and ginger into a bowl. Add the egg and yolks to the melted mixture, then pour over the dry ingredients and mix to a dough. Wrap and chill for 30 minutes.
Roll out the dough on a floured surface and cut out 2 rectangles, 15 x 11 cm (6 x 4½ inches), for the roof. Cut out 2 rectangles, 14 x 8 cm (5½ x 3½ inches), for the sides and 2 squares, 14 cm (5½ inches), for the ends. Trim each end piece into a triangle point running from the centre of the top side to halfway down 2 opposite sides. Cut holes for doors and windows. From the trimmings, make a door and 2 shutters per window.
Place on greased baking sheets. Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 10–15 minutes until colouring around the edges. Transfer to a wire rack to cool.
Spoon royal icing into a piping bag with a writing nozzle. Spread more icing over a silver cake board. Secure the walls of the cottage to the board, gluing sections together with icing. Spread the top edges with icing and secure the roof. Leave for 2 hours to set.
Spread a little royal icing over the roof sections. Knead and roll out the ready-to-roll icing and cover the roof. Use icing trimmings to shape a chimney and snow drifts around the cottage. Using royal icing, pipe icicles at the roof edges and attach and decorate the shutters and door.
Decorate with marshmallows and sweets. Lightly dust the cottage and board with icing sugar.