Bring 4 cups of water to a boil in a large, heavy bottom saucepan.
Add the Kosher salt and then slowly add the quick cooking grits, stirring constantly. Reduce the heat to low and simmer, stirring occasionally, until the grits thicken, approximately 5 to 7 minutes.
Stir in the half-and-half and butter to the grits. The mixture will thicken as it cooks. Bring back up to a low simmer.
Cover the pot and reduce the heat to low for 30-45 minutes, stirring occasionally.
Take the saucepan off the heat and fold in the cheddar cheese.
Garnish with additional grated cheddar cheese and scallions.
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