Line a baking sheet with parchment paper and set aside. In a large bowl, whisk together flour, baking soda, baking powder, sea salt, cinnamon, and nutmeg. Set aside.
In another bowl, mix together granulated white sugar, brown sugar, pumpkin puree, butter, and vanilla until smooth and uniform.
Combine wet and dry ingredients and mix until a dough forms. Cover and refrigerate for 30 minutes or more.
While dough chills, preheat oven to 350 degrees Farenheit. Combine sugar and spices for the chai spice mix in a small bowl.
Using a tablespoon, scoop out chilled dough and roll into 1 ½-inch balls. Roll each ball in the chai-sugar mixture then place on a baking sheet about one inch apart.
Bake cookies for about 12 minutes or until they pass the press test: gently press to top of a cookie. It should yield to gentle pressure then regain its shape. Edges will lightly brown but tops will not brown.
Transfer cookies to a rack to cool.