Bring 6 cups water to a boil in a medium saucepan. Slowly sprinkle the grits into boiling water, stirring constantly with a whisk. Reduce heat to medium, and stir constantly until the mixture is thick, 5 to 7 minutes. Remove the pan from heat, and stir in cheddar, cumin, cayenne, salt, pepper, and scallions.
Pour the mixture into a buttered 13 by 18-inch baking pan, and smooth out to a 1/2-inch-thick layer. Using a 2 1/2-inch-round cookie cutter, lightly mark out 24 circles in the grits. Press a shrimp half into each circle. Cover with plastic wrap, press down lightly to smooth, and chill until set, 1 to 2 hours.
Combine the flour and cornmeal in a small bowl. Using a cookie cutter, cut the grits along the marked lines into rounds, keeping the shrimp centered in each circle. Heat 1 teaspoon butter and enough oil to cover the bottom of a large skillet over medium-high heat. Dredge the cakes in the flour mixture, and saute, 8 at a time, until golden brown, 1 to 2 minutes on each side. Wipe out the skillet, and repeat, adding more butter and oil, until all cakes are cooked. Transfer to a baking sheet lined with paper towels. Top with a scant teaspoon of seven-pepper jelly and scallion greens; serve warm.
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