Step 1Heat the oven to 350°F. Scatter the walnuts in a metal pie tin and roast them until toasted and fragrant, 8-10 minutes. Roughly chop.Step 2Cover the cranberries with boiling water and soak for at least 10 minutes then drain.Step 3Combine the water and yeast in a large mixing bowl and let sit for a few minutes for the yeast to dissolve. Stir in the pumpkin puree, sugar, cinnamon, ginger, nutmeg and salt. Add 3 1/2 cups of flour to form a loose, shaggy batter.Step 4Add the drained cranberries, chopped walnuts, and 1/2 cup additional flour to the dough. Use your hands to squeeze the dough and work in the additional ingredients. The dough will be very sticky and loose at this point. Scrape as much dough from your hands as you can, cover the bowl, and let the dough rise for at least 2 hours or up to 5 hours. It should at least double in bulk during this time.Step 5At this point, you can proceed with making the bread or you can refrigerate the dough for a few hours or up to a day. Chilled dough will be easier to work with and shape into a ball.Step 6Sprinkle your work surface generously with flour and turn the dough out on top. (If making two loaves or rolls, divide the dough now and shape each loaf or roll as follows.) With floured hands, fold the dough in half toward you so the un-floured surface is sealed inside and the outside is coated in flour. If the outside is still sticky, rub it gently with a litte more flour.Step 7Flour your hands again and pick up the round of dough. It should feel fairly loose, but should be firm enough to shape. Begin shaping the dough into a round ball by smoothing the top and tucking the dough underneath (check out this video on shaping round loaves). When the dough feels tight and smooth, set it on a piece of parchment. Let the loaf rise uncovered until puffy and nearly doubled in size, about 45 minutes.Step 8Heat the oven to 450°F. If you have a baking stone, set it in the oven now. If not, set a baking sheet in the oven to preheat.Step 9When ready to bake, slide the dough still on the parchment onto the baking stone with a peel or the back of another baking sheet. (If cooking on a baking sheet, remove the sheet from the oven and quickly lift the bread on top.) Cut a few slash-marks in the top of the loaf with a serrated knife. Bake for 25-30 minutes, until the crust is golden-brown and the loaf sounds hollow when you tap the bottom.Step 10Cool completely before slicing. Baked loaves will keep in a paper bag for several days or can be frozen for up to a month.