You'll need two batches of this dough to make our four-car Gingerbread Train and all its parts -- and still have a little extra left over for nibbling. Mix one batch at a time (rather than doubling our recipe), or the dough will become too difficult to work with.
Sift 3 cups of flour into a large bowl. Combine 2 more cups of flour with the baking soda, salt, ginger, cinnamon, nutmeg, and cloves, then sift the mixture into the bowl. Stir the ingredients, then set the bowl aside.
In another large bowl, beat the butter, brown sugar, and egg until fluffy, about 2 minutes. Add the molasses and beat until evenly blended, about 1 1/2 minutes. Blend in the vanilla extract.
Using a wooden spoon, stir the dry ingredients into the butter and sugar mixture 1 cup at a time. The dough should be firm; if it's not, gradually stir in up to 1/2 cup more flour.
Divide the dough in half. Place each piece in a gallon-size ziplock bag and flatten the dough into a thick rectangle with your hands. Seal the bags and refrigerate for at least 4 hours, preferably overnight.
Repeat steps 1 through 4 with a second batch of dough.
Heat the oven to 350º. Working with one piece at a time, remove the dough from the refrigerator and set it on a generously floured cutting board or work surface. With a lightly dusted rolling pin, roll the dough to 1/4 inch thick, about a 10- by 13-inch rectangle.
Measure and cut the pieces as desired. As you cut, set aside the scraps of dough, then knead them together into a ball. Flatten the ball into a disk and chill the dough for another 45 minutes, then roll and cut out more shapes.
Line a large cookie sheet with aluminum foil, leaving some overhang on each end for easier handling. Dust it lightly with flour.
Transfer the gingerbread pieces to the foil and bake them on the center oven rack until golden brown, about 15 to 17 minutes. Be careful not to overcook the gingerbread, or it will darken and shrink. Lift the foil to transfer the baked cookies to a rack. Allow the pieces to cool completely before taking them off the foil. Let the gingerbread firm up at room temperature for at least 2 hours before attempting to assemble a house or train. You can also store it in an airtight container if you're planning to assemble it another day.