Preheat the oven to 400°. Butter the bottom and sides of a 2-quart souffle dish and coat the surface evenly with the sugar, tapping out the excess.
In a medium saucepan, combine the milk, and half and half, 1/2 cup sugar, and the butter. Bring the mixture to a boil over medium-high heat. Very slowly, to avoid lumps, whisk in the grits and salt. Add the egg yolks to a small bowl and the egg whites to a large bowl. Stir a little of the hot grits, into the egg yolks, to temper, then add the yolks to the pan and whisk to combine. Add the lemon zest, cinnamon and nutmeg. Reduce the heat and simmer, stirring constantly, until the mixture is thickened and cooked through, about 15 minutes.
Using an electric mixer, whip the egg whites to soft peaks. Add the remaining 2 tablespoons of sugar, and continue whipping until stiff peaks form. Fold 1/3 of the meringue into the grits to lighten, and then fold in the remaining meringue. Scrape the batter into the prepared souffle dish and bake in the center oven rack until the souffle is golden but the center still jiggles, 40 to 45 minutes. Serve immediately.