On baking day, take a 1 1/2 pound dough piece (small cantaloupe-size, 1/3 of refrigerated dough recipe from above) from the bucket. Put remaining dough back in refrigerator.
Using plenty of flour, roll out the dough into a 1/4-inch-thick oval. Form the 1/2 cup almond paste into a rope and lay it onto the dough about a 1/3 of the way from the end.
Fold the dough over the almond paste in thirds, so that it forms an S-shape, when you look at it from the end.
Place the loaf on a sheet pan with parchment or a nonstick silicone baking mat and loosely cover with plastic and let it rest for 90 minutes.
Preheat oven to 350°F, with rack in the middle of the oven.
Using a pastry brush, cover risen dough lightly with egg wash. Bake for 35 to 40 minutes.
Cool on wire rack for about 20 minutes.
Sift confections' sugar over top until it is completely covered.