Whisk together flour, cocoa powder, and salt. Beat butter and sugar until pale and fluffy. Add egg and vanilla, and beat until smooth. Add dry ingredients, and beat until combined. Shape dough into 2 disks. Wrap each in plastic, and refrigerate for 30 minutes.
Preheat oven to 350 degrees. Roll out each dough disk to 1/8-inch thickness on a lightly floured piece of parchment. Transfer dough on parchment to baking sheets, and freeze until firm, about 20 minutes. Place templates on dough, and trace with a paring knife to cut out 2 side-wall pieces, 2 pointed side-wall pieces, and 2 roof pieces. Remove excess dough, and freeze house pieces until firm, about 20 minutes.
Bake until just darkening around the edges, 12 to 14 minutes. Transfer sheets to a wire rack, and let cool completely before using.