Turning the speed of the mixer down to slow, add two cups of the flour; then turn off the mixer and add the remaining cup of flour and stir by hand. The dough will be stiff. Transfer the dough to a board coated with a dusting of flour and knead until the dough is no longer sticky, adding more flour if necessary. Divide the dough in half and wrap one half in plastic wrap (to prevent it from drying out) while you begin work on the other half.
Dust your work surface and your springerle mold with powdered sugar. Roll the dough out to 1/4 or 3/8 inch thick. Press the mold firmly into the dough, and then cut your desired shape around the mold. Place the cookie on a baking sheet that is covered with parchment paper. Repeat until the first dough ball is finished; then continue with the second batch of dough. Let the cookies stand uncovered for at least 12 hours (yes, 12 hours).
Bake the cookies, one sheet at a time, at 220 degrees for 30 minutes. Do not let them get brown - if they start browning, turn the oven down to 200 degrees. Note: The baking process works best if the cookies are not on the bottom shelf of the oven. Let the cookies cool on wire racks.