Preheat your oven to 350°F (175°C) and prepare a 9x13 inch baking pan.

In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, chai spices, and salt.

In a large mixing bowl, beat together the eggs and granulated sugar until pale and creamy. Mix in pumpkin puree, melted butter, buttermilk, and vanilla extract.

Gently fold the dry ingredients into the wet mixture until just mixed.

Pour the batter into the prepared baking pan and bake for approximately 35 minutes.

For the frosting, melt the butter in a skillet over medium heat until golden brown and nutty.

While the cake cools, whisk the brown butter with powdered sugar and milk until smooth.

Once cooled, spread the frosting evenly over the cake.

Garnish with sugared chai spices or optional toppings like star anise. Slice and serve.