Mix butter in a stand mixer at medium speed for 1-2 minutes until the colour lightens slightly.
Add sugar and mix at medium speed until creamy.
Add egg and vanilla.
Mix at medium speed until combined.
In a separate large bowl, whisk flour and salt together.
Add flour mixture 1/2 cup at a time to wet ingredients and mix at low speed until combined.
Repeat until the dough comes together and sides of the bowl are clean. (You may not need all the flour).
Roll the dough out between two pieces of parchment paper, place it on an upside-down cookie sheet and pop it into the fridge for about 10-15 minutes to cool.
Preheat your oven to 350.
After the dough is chilled cut out two side walls, two roof panels, two end walls, and two chimney pieces leaving the cutouts in the surrounding dough so it doesn't expand. Use the window and door cutters where you want them on the wall panels. (only indent the door so you know where to ice it). Put them in the oven for 12 minutes, rotating the pan around at the halfway point. (Each oven varies so just be sure to take them out if you notice any edges turning brown)!
Once out of the oven use a knife to cut along all the edges again and to pry out the small window panes while the dough was still warm. Then let it cool before taking all the excess dough away from your shapes. While the pieces cool, make your icing.
Icing Your House
In your mixer, whisk together meringue powder and water for several seconds until it reaches foam-like consistency.
Add powdered sugar, increase speed to medium and beat for about 10 minutes, until stiff peaks form.
Divide the white icing into 3 bowls.
Add colouring a few drops at a time until you reach your desired colour. (A damp paper towel can be placed over the bowls to prevent crusting over while you prepare your colours.)
From here you will add water in 1/2 tsp increments until you reach your desired consistency. Piping consistency: used to outline the cookie prior to flooding it. Also used for details on the cookie- Flooding consistency: used to fill the areas of the cookie.
Scoop icing into tipless bags. Tie the top of the bag in a knot or use a clip/band.
After your cookies are outlined and flooded with white icing, leave the icing to set. You’ll know the area is dry enough to start on the details when it crusts over and loses its shine.
Then, start on your door and shutters. Once those are dry, start to detail. (Waiting until the icing dries helps make that nice 3D effect). Once the door and shutters dry, start on your wreath and garland detail. Before those dry, pop on some cute holiday sprinkles. Then let all the pieces dry completely before attempting to construct your house.
Use the remainder of the white piping icing as glue to put each wall together and once those set ice the roof in place, followed by the chimney. Once together, add some more to icing look like snow (and ultimately hide any flaws in your construction).