Cook tortellini in a large saucepan of boiling water according to packet directions. Drain. Return to saucepan.
Place prosciutto on a lined baking tray and bake at 180°C for 5-8 minutes, until crisp. Remove and break into pieces.
Heat the oil in a large non-stick frying pan over medium heat. Add onion and garlic and sauté for 3 minutes or until softened. Gradually whisk the stock into the Philly* until smooth. Add to the frying pan along with the zucchini and simmer for 5 minutes or until sauce has thickened. Remove from heat. Stir through blue cheese and half the prosciutto. Pour cheese sauce over tortellini and toss to coat. Divide mixture amongst serving plates and top with remaining prosciutto and Parmesan.