Place the flour, ginger, cinnamon and butter in a food processor and pulse until they resemble breadcrumbs (do this in two batches if the bowl is small). Combine the sugar, treacle and egg in a large mixing bowl. Tip in the flour mix and stir, then bring the dough together with your hands. Turn onto a lightly floured surface and knead until smooth. Cover and chill for at least 1 hr.
Heat oven to 180C/fan 160C/gas 4. Line three baking sheets with non-stick paper. Divide the dough into three and roll out on a floured surface to the thickness of two £1 coins. Using the templates, cut out two each for the roof, sides and two pointed end walls. Lift them onto the baking sheets. Re-roll scraps of dough, then cut out the small trees. Bake for 12 mins or until just firm. Leave to firm up for 5 mins, then transfer to a wire rack to cool.
To assemble the house, pipe a door on an end wall and a window on a side wall, using the squeezy icing. Pipe icing generously along one long edge of one side wall and stick it to the board. Repeat with an end wall, join the corners with a line of icing, then fix a flake bar to the base as a 'foundation'. Stick the remaining walls together. Use another flake bar to support the other end wall. Fix on the roof pieces, then leave overnight to set.
Stick the marshmallows all over the roof, using the decorating icing as glue. Fix chocolate buttons around the door and to cover the corner joins. Pipe icicles along the front edge of the roof using the squeezy icing – start each one with a small pea-sized blob of icing. Pull the icing nozzle downwards and away from the blob – the icing will break off in a jagged 'icicle'. Alternatively, decorate with a line of white chocolate buttons.
Mix the icing sugar with drops of water until you have a thick but spreadable icing. Spread this over the board and decorate with the lollipops (fastened to soft sweets), sweets, chocolate buttons and gingerbread trees. Dust lightly with icing sugar for a snowy effect.
NOTE: To make the templates draw each shape on card or paper, using the following measurements.
Side walls: 16cm x 10cm.
Roof walls: 19cm x 12cm.
End walls: Total height 18cm to the apex. 10cm tall to the top of the box. Angled line 11cm long.