Preparation Put oven rack in middle position and preheat oven to 400°F. Lightly oil a 9 1/2-inch (6-cup capacity) pie plate. Cook onion in 2 tablespoons oil in a deep 10-inch heavy skillet over moderate heat, stirring occasionally, until edges are golden, 3 to 4 minutes. Add garlic and cook, stirring, 1 minute. Add beef and cook, breaking up large lumps, until no longer pink, 4 to 5 minutes. Add sugar, spices, and 1 teaspoon salt and cook, stirring, 1 minute. Add tomatoes with juice and briskly simmer, stirring occasionally, until liquid is reduced to about 1/4 cup, 8 to 10 minutes. While beef simmers, whisk together cornmeal, flour, baking powder, and remaining 1/4 teaspoon salt in a medium bowl. Whisk together milk, egg, and remaining 2 tablespoons oil in a small bowl, then stir into cornmeal mixture until just combined. Fold in 1/2 cup cheese. Spoon cooked spiced beef into pie plate with a slotted spoon, reserving juices in skillet. Skim off and discard fat from juices if desired, then pour juices over beef in pie plate. Spoon 4 mounds of corn bread batter over beef, then sprinkle remaining 2 tablespoons cheese over batter. Bake until a wooden pick or skewer inserted into center of corn bread comes out clean, 15 to 25 minutes. Serve cobbler warm.