In a medium sauce pan heat the milk until just boiling. Whisk in the corn meal and salt, stirring quickly.
Drop the heat to low and continue to whisk until thickened. Remove from heat, set aside and let cool, about 30 minutes.
Heat oven to 350 degrees Fahrenheit and grease a 2-quart baking dish.
In a mixer fitted with a paddle attachment combine the cornmeal mixture, mashed sweet potato and the brown sugar and beat on low speed until just combined.
With mixer still on low, pour in the melted butter. Mix for 1 minute then turn off mixer and scrape down the bowl.
After scraping add flour, baking powder, eggs, chile and adobo liquid to the bowl. Mix on medium speed for 2 minutes then pour the batter into the prepared 2-quart baking dish.
Cook for about 1 hour and 20 minutes, until the spoonbread puffs up a bit and browns.
You can find chipotles in adobo in cans at specialty and Latin markets