1. Place first 4 ingredients in a 13- x 9-inch baking dish, tossing to coat. Squeeze juice from lemons over shrimp mixture, and stir. Add lemon halves to pan. Sprinkle evenly with parsley; dot with butter.
2. Bake at 375° for 25 minutes, stirring after 15 minutes. Serve in pan.
*3 lb. frozen peeled, large raw shrimp, thawed according to package directions, may be substituted. Prepare recipe as directed, reducing pepper to 1/2 tsp.