Caprese Mac and Cheese

Name: Caprese Mac and Cheese
Ingredients: * 100g butter; * 1/2 cup flour; * 1 litre milk, warmed with 1 bay leaf, 1/2 onion and 5 black; peppercorn; * pinch of nutmeg; * 150g gruyere other strong, mature cheese, grated; * salt and white pepper to taste; for the tomato layer; * 400g tin whole peeled tomato; * 1 teaspoon sugar; * 1 teaspoon salt; for the mac and cheese; * 500g pasta of your choice (i used a spiral shaped tube), cooked plus 1; cup of cooking water reserved; * 8 ripe tomato,; * 1/2 cup basil pesto