Combine first 3 ingredients; spoon evenly into 4 (1 1/2-cup) lightly greased individual baking dishes. Set aside.
Peel shrimp, and devein, if desired.
Combine baking mix and Cajun seasoning. Dredge shrimp in mixture.
Melt 1 1/2 tablespoons butter in a large nonstick skillet over medium heat; add half of shrimp, and cook, stirring constantly, 3 to 5 minutes or just until shrimp turn pink. Repeat with remaining 1 1/2 tablespoons butter and shrimp.
Spoon shrimp evenly over tomato mixture. Sprinkle evenly with cheese.
Broil 5 inches from heat 3 minutes or until cheese is melted and lightly browned. Garnish, if desired.
Note: Recipe may also be prepared in a lightly greased 11- x 7-inch baking dish. Reduce dressing to 1/4 cup and cheese to 1 1/2 cups. Bake at 425° for 5 to 8 minutes or until cheese is melted and lightly browned. For testing purposes only, we used Bisquick all-purpose baking mix and McCormick's Cajun seasoning.