01 - Submerge the dried corn husks in warm water for a minimum of 30 minutes until pliable. Drain thoroughly and set aside.
02 - Combine pumpkin purée, packed brown sugar, ground cinnamon, nutmeg, cloves, ginger, vanilla extract, and salt in a bowl. Mix until a uniform, smooth consistency is achieved. Reserve for assembly.
03 - In a large mixing bowl, whisk together masa harina, granulated sugar, salt, and baking powder. Incorporate softened butter and vegetable oil, blending with hands or an electric mixer until the mixture is coarse and crumbly.
04 - Gradually pour in the warm milk or plant-based milk, mixing thoroughly until a soft, spreadable dough forms. Dough should be moist but easily manipulated; adjust with additional milk if necessary.
05 - Pat each corn husk dry. Spread approximately 2 tablespoons of prepared masa dough onto the wide end of each husk, leaving a 1-inch margin at the sides and top.
06 - Deposit 1 heaping tablespoon of pumpkin filling in the center of the masa upon each husk.
07 - Fold the sides of the husk gently over the filling, then tuck the bottom upward to enclose. Secure with a thin husk strip if preferred.
08 - Position filled tamales upright in a large steamer pot fitted with a rack. Cover tamales with damp towel or additional husks to prevent drying.
09 - Steam tamales over gently simmering water for 75 to 90 minutes, replenishing water as needed. Masa is ready when it releases easily from the husk.
10 - Remove cooked tamales from steamer and allow to cool for 10 minutes prior to serving.