I folded it in half lengthwise and marked a triangle at the top to cut out for the roof. I also cut the front triangle off so the front is a square and the back is the house shape.
I then unfolded the card and glued a coordinating paper to the other side, being careful to use a bone folder to re-fold the card so it closes.
That's it for the basic card. I went further with these and covered half of a paper slide mount with another coordinating paper for the window and edged the whole card with red stamp ink for contrast.
Now all that's left is to add the images I want in the window and any other embellishements and they will be ready to go.