These make a welcoming Southern appetizer for any gathering.
Fill a large bowl with ice water; set aside. Bring a medium saucepan of water to a boil. Blanch the shrimp until opaque, 1 to 2 minutes. Transfer shrimp to ice bath until cool. When cool, peel and cut in half lengthwise along the vein. Discard vein; set aside shrimp.
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 10-by-15-inch jelly-roll 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 1 halved shrimp 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 the cookie cutter, cut the grits along the marked lines into rounds, keeping the shrimp centered in each circle. Heat 2 teaspoons butter and 2 teaspoons oil in a large skillet over medium-high heat. Dredge the cakes in the flour mixture, and saute, eight 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 or a plate lined with paper towels. Top with a scant teaspoon of seven-pepper jelly and scallion greens; serve warm.
The grits can be cooked and the cakes assembled in advance and kept refrigerated until needed. Do not worry if shrimp loosen from cakes as they cook; simply press them back into cake.