Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
In a large bowl, combine the melted butter, brown sugar, and granulated sugar. Mix until smooth.
Add the vanilla extract, egg, and egg yolk to the butter and sugar mixture. Beat until light and creamy.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the chocolate chips evenly throughout the dough.
Divide the dough in half. Roll out one half between two sheets of parchment paper to about 1/4 inch thickness.
Using a printed template or freehand, cut out the shapes for the cookie house panels: two rectangles for the walls, two rectangles for the roof, and two triangles for the roof ends.
Transfer the cutouts on the parchment paper to the baking sheets.
Repeat rolling and cutting with the remaining dough for backup pieces or additional decorations.
Bake the cookies for 12 to 15 minutes or until the edges are golden brown. Allow cookies to cool completely on the baking sheets.
While cookies cool, prepare the royal icing by beating the egg whites and cream of tartar in a large bowl until frothy.
Gradually add the powdered sugar, beating on low speed until combined, then on high speed until stiff peaks form and the icing is smooth and thick.
Transfer the royal icing to a piping bag fitted with a small round tip or a resealable plastic bag with the corner snipped.
Assemble the cookie house by piping royal icing along the edges of the wall pieces and pressing them together. Hold until set, then attach the roof pieces similarly.
Use remaining royal icing to pipe decorative details such as window frames, door outlines, and roof shingles.
Allow the assembled house to dry and set completely for at least 4 hours before moving or displaying.