Sprinkle yeast into a small bowl and pour the warm water on it. Let stand for 10 minutes, then stir to dissolve.

Mix flour, cinnamon, and cardamom in a large bowl. Make a well in the center and pour in yeast/water mixture.Using a wooden spoon, incorporate some of the flour into the water–just enough to form a soft paste. (Don’t try to completely incorporate–there should be quite a bit of dry flour left at this point.)
Cover bowl with a towel and leave until frothy and risen, about 20 minutes.

In a separate bowl, whisk together the sugar, pumpkin, oil, egg, and salt.
Add to the risen flour mixture and combine thoroughly. Turn dough out onto a lightly floured surface and knead for 5-10 minutes until the dough is pliable. (If it’s too wet, keep adding flour in small amounts.)

Let dough rest 2-3 minutes. Meanwhile, lightly oil the bowl, put the dough in it and re-cover with the towel. Let dough rise in a warm place until it has tripled in size, 2-3 hours.
Punch down dough, knead it a bit more, and cut it into two equal pieces. Cut each of the two pieces into three equal pieces (You should have 6 total pieces at this point).

Roll each piece into a straight rope.
Braid three ropes together and repeat so that you end up with two braided loaves.

Sprinkle baking sheets with a little cornmeal, or line them with parchment paper. Place loaves on the sheets, cover, and let rise until doubled in size, about 40 minutes. Glaze loaves with extra beaten egg. Bake at 350F for about 20 minutes, or until golden brown.