In a large bowl mix 3/4 cup of warm water, yeast and sugar and let it rest for 5 minutes.
In the meantime mix 3/4 cup of water, butter and salt in a small pot over medium heat and stir until the butter is melted. If it is too hot let it cool until you can insert a finger without burning yourself. (Or you could use a thermometer to know when the water reaches 150ºF, but I trust my finger better)
Pour the water in the large bowl with the yeast and whisk very well.
If you have one of those big mixers, attach the dough hook and turn to medium speed. Add one cup of flour at a time. Add pumpkin puree and spices (optional) and let it beat the dough at medium speed for 10 minutes. If the dough is too sticky add more flour as necessary.
If you don't have a stand mixer, mix all the ingredients with your hand in the bowl until you can turn the dough into a floured surface and knead for 10 minutes. Add more flour if necessary.
If you are using the dough for pizza, divide it in 4 parts and place on a greased sheet. Cover with plastic wrap and refrigerate. Remove from the fridge at least one hour before you are ready to form your pizza crust and bake.
If you are using the dough for rolls, place it in a bowl and cover. Let it double in size once (1 hr approximately at 75ºF) Punch it in the middle to deflate. Transfer to a flour surface and cut it in 16 pieces. Place the rolls on a greased baking sheet and cover. Let it rise for 30-40 minutes and bake at 350°F for 15 minutes or until they start to turn golden brown.
Recipe by Ben's blog at http://whatscookingmexico.com/2008/11/21/pumpkin-dough/