Bake potatoes at 375° for 1 hour or until tender; cool 10 minutes. Reduce oven temperature to 350°.
Cut potatoes in half lengthwise; carefully scoop out pulp into a large bowl, leaving shells intact. Stir together pulp, sour cream, milk, and butter; stir in basil and next 3 ingredients.
Coat insides of potato shells with cooking spray. Spoon potato mixture evenly into shells; sprinkle evenly with tomato and cheese.
Bake potatoes at 350° for 10 minutes or until thoroughly heated and cheese is melted.
Note: To make ahead, place unbaked stuffed potato halves, covered, in the refrigerator. Bring potato halves to room temperature before baking at 350º.