You can use a combination of sweet potato and squash puree for this recipe, or just one or the other. The total puree should weigh 1 lb. 

INGREDIENTS

•  2 cups AP flour
• 1/2 teaspoon salt
• 1 teaspoon baking soda
• 1/2 teaspoon baking powder
• 1 teaspoon cinnamon
• 1 teaspoon nutmeg
• 1.5 sticks of butter, softened
• 2 cups sugar
• 2 eggs
• 1 - 1.5 lb squash and/or sweet potatoes
• optional, but recommended: chocolate chips and/or chopped walnuts

INSTRUCTIONS
For Puree

1. Preheat oven to 375F with oven rack in upper third.
2. Prepare squash: cut in half and scoop out seeds; and/or prepare sweet potatoes: peel and cube.
3. Toss sweet potatoes with olive oil, and/or brush cut side of squash with olive oil.
4. Put squash and/or sweet potatoes on a baking sheet. (If cooking both on same sheet, put on different sides as they may take different amounts of time to cook.)
5. Bake in oven for approx 1 - 1.5hrs, until a fork slides easily into diced vegetables.
6. Remove from oven and blend into puree. Don't have a blender? Wait until cool, then mash with very clean hands or potato masher. 

For Muffins

1. Lower oven temp to 325°F and place oven rack in middle.
2. Grease 2 muffin pans or 2 8 x 4" loaf pans and lightly dust with flour or cocoa powder.
3. Whisk dry ingredients in a bowl: flour, salt, baking soda, baking powder, spices. 
4. Cream sugar and butter together in a large bowl until combined.
5. Add eggs and beat well to combine, until fluffy.
6. Add puree and continue to stir until combined. (If the mixture looks mealy, that's okay!)
7. Slowly add dry mixture to wet mixture, combining a little at a time to prevent clumping. Mix in chocolate chips and walnuts if desired. 
8. Scrape batter into pans and bake for 45-50 min (muffins) or 65-75 min (loaves) until tester comes out clean.
9. Let cool in pan for 10 min, then turn out onto wire rack and cool.
10. Eat within a few days or wrap tightly in foil and freeze, eating within 1 month.