Mix the flour, ginger, cinnamon, baking soda, and salt in a bowl.
In a second bowl, beat the butter and brown sugar until smooth. Add the molasses and egg and mix until combined.
Stir the dry ingredients into the wet mixture until a dough forms. Wrap the dough and chill it for 30 minutes.
Roll the dough to ¼ inch thick on a floured surface. Cut into house shapes with a cookie cutter.
Place the shapes on a baking sheet and bake at 350°F for 8 to 10 minutes. Let them cool completely on a wire rack.
Whisk the powdered sugar, meringue powder, and water until the icing reaches a pipeable consistency.
Pipe outlines and details onto the cooled cookies to create haunted house designs. Let the icing set before serving.