Preheat the oven to 200˚C. Place the tomatoes on a roasting tin and season with salt and drizzle with olive oil.
Roast for 15-20 minutes until they start to blister. Remove and set aside until needed.
In a medium size saucepan, bring water and milk to the boil. Add packet contents and stir continuously until boiling. Reduce heat and simmer uncovered for 8-10 minutes, stirring occasionally.
Remove from the heat, add the basil pesto and mix through. Leave the to stand on the hot plate for 2 - 3 minutes before serving. Sauce will thicken and pasta will soften upon standing. Top the pasta with the roasted tomatoes and fresh basil leaves. Grate a little Parmesan over just before serving.