Preheat the oven to 425°F and line a 12-muffin pan with baking cups. Grease the bottoms if necessary to keep the muffins in place.
Melt the butter and allow it to cool while you combine the rest of the ingredients.
In a mixing bowl, blend the almond flour, coconut flour, sweetener, chai spices, baking powder, baking soda and salt.
In another bowl, whisk the eggs, then add the cooled melted butter and vanilla extract. Stir to combine thoroughly.
Pour the egg mixture into the dry ingredients, blend together, then fold in the pumpkin puree to combine without overmixing. Work quickly to prevent the batter from thickening further.
Use an ice cream scoop or a 1/4 cup measuring cup to divide the batter evenly among the 12 baking cups.
Place the pan on the middle rack in the oven preheated to 425°F for 10 minutes. This initial high temperature will help the muffins rise properly. After 10 minutes, reduce the oven temperature to 325°F and continue baking for 8-10 minutes without opening the oven door. This will ensure that the muffins bake evenly and rise to perfection.
Insert a toothpick in the middle of one of the muffins to check for doneness. If it is still soft in the middle, bake for another five minutes.
After the muffins are baked, allow them to cool in the muffin pan for 10 minutes. This will help them set and firm up before you transfer them to a wire rack to cool completely.