In a large saucepot, melt
the butter and add the oats. Stir for 2 minutes to toast. Add the boiling water and reduce heat to a simmer. Keep at a low simmer
for 25 minutes, without stirring.
Combine the milk and half of the buttermilk
with the oatmeal
. Stir gently to combine and cook for an additional 10 minutes. Spoon into a serving bowl and top with remaining buttermilk, brown sugar, and cinnamon