I processed my own pumpkin that I got at the farmers' market (see how to do it yourself here!) but you can use canned pumpkin if you like...try to get organic if possible, though!
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Modified from Babycakes NYC recipe
2 1/2 cups gluten free all-purpose flour (or whole wheat pastry flour if you like)
2 tsp baking powder
2 tsp baking soda
1 tsp sea salt
1 tsp xantham gum (use tapioca or arrowroot if unavailable)
1 tsp cinnamon
1/2 tsp allspice
1/2 tsp nutmeg
1/4 tsp cloves
1/2 c coconut oil, melted
2/3 cup agave nectar
2/3 cup almond milk
1 tsp vanilla extract
2 Tbs ground flaxseed + 2 Tbs warm water
1 1/2 cup pumpkin puree
Preheat oven to 375 F. Lightly oil a loaf pan.
In a large bowl, sift together the dry ingredients (flour through cloves). Create a well in the center of the bowl and add in the wet ingredients. Whisk the wet ingredients together and incorporate into the dry ingredients, until completely mixed. Fold in the walnuts.
Pour into the oiled loaf pan; the batter is thick, so use a spoon to press the batter all the way down into the pan and ensure all air bubbles are pushed out. Smooth the top and sprinkle with extra cinnamon and walnuts if desired.
Bake for 30 minutes, rotate pan 180 degrees in the oven, and bake 20 more minutes, until an inserted toothpick comes out clean and the bread springs back slightly when touched.
Let cool in the pan at least 30 minutes before removing.