Heat a covered big pot of water to boiling on high.
Meanwhile, in another pot, whisk cornflour and ¼ cup milk until smooth; add garlic and slowly whisk in remaining milk. Heat to boiling on medium-high, whisking constantly.
Boil for 2 minutes or until thickened, whisking constantly. Reduce heat to medium-low.
Add pasta and 1 teaspoon salt to boiling water. Cook for 2 minutes less than minimum time given in instructions. Drain well.
While pasta cooks, remove and discard garlic from milk mixture; add cheeses in two batches, stirring until smooth after each batch. Stir in spinach, peas, cooked pasta and ¼ teaspoon each salt and freshly ground black pepper. Cook for 2 minutes or until pasta is al dente, stirring.
Each Serving About 2 081kJ, 29g protein, 43g carbohydrate, 19g total fat (11g saturated), 8g fibre, 35mg cholesterol, 583mg sodium.