Preheat the oven to 425°F. Rub 1 chicken breast with 1 tablespoon olive oil, 1/2 teaspoon garlic powder, 1/2 teaspoon smoked paprika, 1/4 teaspoon oregano, 1/4 teaspoon salt, 1/4 teaspoon pepper, and 1 tablespoon lemon juice. Roast 18 to 22 minutes, until 165°F. Rest 5 minutes, then slice.
Cook 6 ounces rigatoni in well-salted water until al dente. Reserve 1/4 cup pasta water and drain.
Heat 1 tablespoon olive oil in a large skillet over medium heat. Add 2 minced garlic cloves and cook 30 seconds. Add 1 diced heirloom tomato and cook 5 to 7 minutes, until it breaks down into a chunky sauce. Season with salt, pepper, and optional red pepper flakes.
Add the rigatoni and toss. Use reserved pasta water a tablespoon at a time if the sauce needs loosening. Turn off the heat and fold in 2 tablespoons torn basil.
Divide the pasta between two bowls. Top with sliced chicken and 4 ounces fresh mozzarella. Let the residual heat soften the cheese, then finish with optional balsamic glaze or olive oil.