In a small saucepan, melt together the butter, sugar and syrup.
Add the melted butter/sugar mixture to a large bowl, sieve over the flour, salt and ginger and mix well to combine.
Allow the mixture to cool for 15-20 minutes until it’s thick enough to handle, then roll out the gingerbread between two sheets of nonstick parchment paper.
Refrigerate the gingerbread mixture until it’s firm to the touch, then either use a knife and templates to cut out your designs, or use gingerbread house cookie cutters. Sketch out your designs beforehand, and make sure to make spare panels in case you have any assembly breakages. You’ll need four walls and two roof panels, as well as any additional decorations for your scene like trees, snowmen, windows and doors. Refrigerate the cut pieces until very cold as this will help them not to spread.
Bake the gingerbread for 10-12 minutes until golden brown. It will still feel soft to the touch, but it will set up when it’s cooled on a wire rack fully.
Bake the remaining gingerbread panels and allow them to cool on a wire rack.
Meanwhile, make the royal icing by beating together the egg whites, sugar and cream of tartar until thick and glossy, about 5 minutes. It should be so thick that the whisk can stand upright unattached to the mixer. Add the icing to a piping bag, using a nozzle coupler if possible so you can use multiple tips with the same bag.
Place a 30cm or larger, round cake board onto your work surface. Pipe the icing along the base of one side panel and position on the board. Prop the piece up temporarily with a support, like a cup or glass. Position it against the side panel and prop up with another tea cup. Allow to set and firm up for at least 20 minutes.
Pipe the icing along one side and the base of the other side panel. Position it against the front and prop up with another cup. Pipe the icing along the base and both sides of the back panels. Position against the side panels and leave to dry for 20 minutes.
Remove the supports, and pipe icing along the top edges of the walls and panels and place one half of the roof in position. Repeat for the otherside, holding firmly until the icing starts to dry. Allow to dry completely, at least 30 more minutes.
Ice the doors, windows, chimney and any other decorations as desired. Allow the house to dry fully, then add fairy lights or tea lights inside.