Preheat the oven to 350 degrees.
Gather the ingredients.
Lightly coat the bundt quartet pan or loaf pans with baking spray.
Whisk together flour, baking soda, salt, cinnamon, nutmeg, cloves, flaxseed, and chia seeds in a medium-size mixing bowl.
In a separate large-size mixing bowl, whisk together brown sugar and softened butter until fully incorporated and crumbly.
Add two eggs to the brown sugar and butter mixture and whisk until evenly distributed.
Whisk to combine the buttermilk or sourdough discard mixture into the brown sugar, butter, and eggs until silky smooth.
Add ⅓ of the flour mixture from the medium size mixing bowl into the large mixing bowl and whisk until fully incorporated.
Add ½ of the pureed pumpkin to the large mixing bowl and whisk until fully incorporated.
Repeat this process of alternating the flour mixture and the pumpkin, making sure to whisk until no dry clumps appear in the batter.