Combine the powdered sugar and meringue powder in a medium or large bowl and add the 2 Tbsp of water. Use an electric mixer to beat at full speed until the icing is smooth. If it's too dry and not smooth, add the 3rd Tbsp of water.

Trim 2 pop tarts for the front and back (1 & 2) of the house to have a triangle on top. Discard the pieces you cut off.

For the 2 sides (3 & 4) of the house, make sure the height matches up with the height of the front and back of the house that you trimmed.

The 2 roofs (5 & 6) stay whole.

The chimney (7) is hard to describe so it's best to look at the picture. Cut it in half, short wise. Then 1/3 off of each half and set those aside. The larger 2/3 of both halves, cut an inverted triangle to fit on top of the roof. The chimney doesn’t have to be perfect because you will trim it again to be flush with the roof of the house when you’re ready to stick it on. 

Pipe the icing on the SIDES of pop tart 1 & 2, the front and back of the house. Stick pop tarts 3 & 4, the sides of the house, to the piped icing. Pipe more icing on top of the whole house to stick on pop tarts 5 & 6, the roof of the house. 

Stick on pop tart 5, one roof, and pipe a line of icing on the top edge to connect pop tart 6, the other roof. Reinforce the whole house with extra icing all around. 

You can see that the chimney may not fit properly so just go ahead and trim down the back piece to make it fit and look right. Then make the front counterpart identical to that piece and the make sure the height of the sides of the chimney match the height of the front and back of the chimney. 

Pipe the icing on the bottom of each piece and on the sides of the sides of the chimney. Stick them all onto the top of the house, towards the back and then reinforce with more icing all around. 

You should have some long, thin scraps from pop tarts 3 & 4, the sides of the house. Trim the height down to make a front door. Pipe icing on the back of the pieces and stick them to the front of your house. 

Cut little pieces of chocolate to make a little pathway in front of the house. Then pipe icing around the pathway to resemble snow. I added a touch of sparkly clear sprinkles. 

To make the "snow" I just piped icing all around the edges of my house and sprinkled on some more that clear sparkly sprinkles. I used the same icing consistency and piping tip as before.

To make the wreath, smash down a mini marshmallow until it’s as flat as it gets. Pipe a ring of icing around the edge and then dip it into a bowl of sprinkles.

After I was done with everything, I added 1 teaspoon of water to my leftover icing and dumped it around the rest of the house.

Stick some candy canes and frosted animal crackers around and decorate however else you'd like!