This is a terrific light dessert. If you leave off the cream-cheese topping, it becomes a lovely accompaniment to roast chicken or pork.
Preheat oven to 400 degrees. Place butter in a 3-quart shallow baking dish; melt in preheating oven, about 3 minutes.
Add honey and orange juice to dish; stir until combined. Arrange plums, cut side down, in baking dish. Bake until tender and juicy, 25 to 30 minutes, turning plums over during final 10 minutes of baking and spooning juices over fruit. (If needed, add 1 to 2 tablespoons water to dish to prevent scorching.)
Meanwhile, in a small bowl, stir together cream cheese and milk until blended. Spoon cream-cheese mixture on plums, and drizzle with pan juices. Serve plums warm or at room temperature.