How to Make It
Bring 4 cups water, 1 cup whole milk, and 1 1/4 tsp. kosher salt to a boil in a medium saucepan over medium-high. Gradually whisk in 1 cup uncooked stone-ground grits; return to a boil. Reduce heat to medium-low, and simmer, stirring occasionally, until creamy and thickened, 25 to 30 minutes.
Cook 4 oz. diced pancetta in a large skillet over medium, stirring often, until browned and crisp. (You will have about 1/2 cup cooked pancetta.) Remove with a slotted spoon, reserving 2 Tbsp. drippings in skillet. Chop 2 medium-size sweet onions. Cook in reserved drippings over medium-high, stirring constantly until caramelized, 15 to 20 minutes. Stir in 1 1/2 Tbsp. minced fresh sage.
Remove grits from heat, and stir in 3/4 cup whole buttermilk and 2 Tbsp. unsalted butter. Stir onions and pancetta into warm grits. Sprinkle servings with crumbled blue cheese.