Adjust rack to middle position and preheat oven to 450 degrees. Wash and dry produce.

Halve tomatoes. Gently separate ravioli.

Coat oven-ready tray with nonstick cooking spray.

In prepared tray, combine cream sauce base, pesto, ¼ cup water, and pepper. Add tomatoes and ravioli; stir until coated. Sprinkle evenly with mozzarella. (For 4 servings, evenly divide ingredients between two trays, using ¼ cup water per tray.) 

Lightly coat a large piece of aluminum foil (two large pieces of foil for 4 servings) with nonstick cooking spray. Cover tray tightly with foil, coated side down. Bake on middle rack (be sure your oven has preheated!) until ravioli are tender, 20-25 minutes. (For 4, bake two trays side by side on middle rack.)

When ravioli bake is almost done, halve and toast ciabatta until golden brown. Immediately spread with 1 TBSP butter (2 TBSP for 4); halve ciabatta on a diagonal.

Remove and discard foil from ravioli bake (careful—watch out for steam!). Return to middle rack and continue to bake, uncovered, until cheese is browned, 5 minutes. Taste and season with salt and pepper if desired.

Divide ravioli bake between shallow bowls and serve with ciabatta toast on the side.