1. Boil ten small potatoes until cooked but not falling apart and chop into bite-sized pieces.
2. Boil 75g of troffie pasta per person, in a large saucepan of salted water, for fourteen minutes or until al dente.
3. Halve 75g of french beans per person and add them to the water cooking the pasta about halfway through.
4. When cooked, drain the pasta and beans, reserving a ladle of cooking water.
5. Add the potatoes to the pasta and beans and stir one teaspoon of pesto per person. Coat thoroughly and loosen the mixture if needed by adding the saved cooking water.
6. Season to taste with parmigiano regiano and serve.