Preheat oven to 375 degrees F. Coat a large nonstick skillet with cooking spray. Heat over medium heat. Add carrots, leeks, and garlic; cook 6 minutes or until tender. Place milk and flour in a screw-top jar; shake until combined. Add milk and chicken broth to skillet; cook and stir until slightly thickened and bubbly. Remove from heat. Whisk in cream cheese until melted. Stir in lemon juice and lemon peel. Season to taste with salt and pepper.
Spoon rice into a 2-quart baking dish; break up any clumps. Pour cream cheese mixture over rice. Pull meat into large chunks. Arrange over rice mixture, gently pressing pieces in. In a small microwave-safe bowl melt butter in the microwave, about 30 seconds. Add panko; stir to coat. Sprinkle over casserole. Bake 15 to 18 minutes or until golden brown. Sprinkle with fresh parsley and lemon peel.