Bring a large pot of salted water to a boil. Add the orzo pasta and cook according to package directions (usually around 8-10 minutes) until al dente. Drain the orzo well and set aside.

Heat the olive oil in a large skillet or Dutch oven over medium heat. Add the chopped onion and cook until softened and translucent, about 5-7 minutes.

Add the minced garlic and red pepper flakes (if using) to the skillet. Cook for another minute.

Pour in the crushed tomatoes and bring to a gentle simmer. Season with salt and freshly ground black pepper. Let it simmer for about 10-15 minutes.

Remove the skillet from heat and stir in the pesto and heavy cream. Adjust seasoning as needed.

Add the cooked orzo to the skillet with the tomato-pesto sauce and stir well to combine.

Pour half of the orzo mixture into a greased 9" x 13" baking dish. Arrange half of the mozzarella and half of the tomatoes over the orzo.

Pour the remaining orzo mixture over the mozzarella and tomatoes.

Arrange the remaining mozzarella slices and cherry tomatoes on top and sprinkle with grated Parmesan.

Preheat the oven to 375°F (190°C). Bake for 20-25 minutes or until the cheese is melted and bubbly and the top is golden brown.

Let it rest for 5-10 minutes before serving.

Garnish with fresh basil leaves before serving.