Meanwhile, in a large skillet over medium heat, melt 1 tablespoon butter. Add garlic, shrimp, and 2 tablespoons parsley. Cook until shrimp is pink and no longer opaque, 2 minutes per side. Transfer shrimp to a plate. (Keep juices in skillet.)
Add remaining 2 tablespoons butter to skillet to let melt, then add flour and whisk until golden, 1 to 2 minutes. Add milk and chicken broth and bring to a simmer. Stir in 3/4 cup mozzarella and 1/4 cup Parmesan until creamy. Season with salt and pepper.
Return shrimp to skillet and add tomatoes and toss. (Add more milk if mixture is too thick.). Then put it aside
Fill the rice on the bottom of the ceramic bowl and the pour the shrimps on top of it.
Sprinkle with remaining 1/4 cup mozzarella and 2 tablespoons Parmemsan and bake until melty, 5 to 7 minutes. Broil 2 to 3 more minutes until top is golden (watch it carefully so it doesn’t burn!).
Garnish with remaining tablespoon parsley and serve.