Step 1: Prepare the Dough

• In a large mixing bowl, dissolve the yeast and sugar in warm water. Let it sit for 5-10 minutes until frothy.
• Add the pumpkin puree, vegetable oil, 2 eggs, salt, cinnamon, and nutmeg to the yeast mixture. Mix until well combined.
• Gradually add the flour, one cup at a time, mixing well after each addition, until a soft dough forms.

Step 2: Knead and Rise

• Turn the dough out onto a floured surface and knead for about 8-10 minutes until smooth and elastic.
• Place the dough in a greased bowl, cover with a clean kitchen towel or plastic wrap, and let it rise in a warm place for 1-1.5 hours, or until doubled in size.

Step 3: Shape the Challah

• Once the dough has doubled in size, punch it down to release the air bubbles.
• Divide the dough into two equal portions. Divide each portion into three equal parts and roll them into ropes, about 16 inches long.
• Braid the ropes into two loaves, tucking the ends under, and place them on a parchment-lined baking sheet.
• Cover the loaves with a clean kitchen towel and let them rise for another 30-45 minutes, or until puffy.

Step 4: Bake

• Preheat the oven to 350°F (175°C).
• In a small bowl, beat the remaining egg and brush it over the risen loaves. Sprinkle with sesame seeds or poppy seeds if desired.
• Bake the challah for 25-30 minutes, or until golden brown and hollow-sounding when tapped on the bottom.
• Remove from the oven and let cool on a wire rack before slicing and serving.