Place the raw chicken breasts in the crockpot, then add the crushed tomatoes, diced tomatoes, chicken broth, tomato paste, garlic, onion, Italian seasoning, and dried basil. Stir so the chicken is coated and you can see a thick tomato base around it.

Cook on Low for 5-6 hours, or High for 3 hours, until the chicken is tender and easily shreds with a fork. You should see gentle bubbling through the broth and softened onion pieces.

Remove the chicken from the pot, shred it, and return the shredded chicken to the soup. The broth should look cohesive with a darker tomato color after the chicken is back in.

Add the penne or rigatoni to the pot and cook on High for 25-30 minutes, until the pasta is tender. The soup should thicken slightly as the pasta absorbs broth.

Top each bowl with shredded mozzarella and grated parmesan, then broil briefly or microwave briefly until the cheese melts and turns glossy. Look for melted, lightly blistered spots on the mozzarella.

Garnish with fresh basil and garlic breadcrumbs, then season with salt and pepper to taste. Serve immediately while the breadcrumbs stay crisp and the cheese stays melted.