Stir in the garlic, salt, black pepper, frozen peas, pimientos with liquid, entire box of uncooked pronto elbow macaroni, and three cups cold water; stir.
Cook on high for ten minutes, stirring occasionally, until liquid dissipates and macaroni is al-dente.
Turn heat to low and stir in condensed soup, drained tuna, milk, and shredded Parmesan.
Cover and simmer for five minutes.
Stir casserole and top with crushed Ritz crackers.