Process tomato with a hand-held blender until a coarse purée forms, set aside. Heat oil in a large saucepan over medium heat, add onion and garlic and sauté until tender (8-10 minutes). Add tomato and basil, reduce heat to very low and simmer until thick and flavours have developed (1½-2 hours). Season to taste and keep warm.
For pasta dough, process flour and a pinch of salt in a food processor to combine, add eggs and process until a dough forms (1-2 minutes). Turn onto a lightly floured surface and knead until smooth (3-5 minutes). Wrap in plastic wrap and set aside to rest at room temperature (1 hour). Divide dough into 4, then, working with one piece at a time, lightly flour and feed through a pasta machine, starting with rollers at the widest setting, reducing settings notch by notch until pasta is 3mm thick. Pass through a spaghetti cutter attachment, dust lightly with semolina and place on a tray lined with baking paper.
Cook spaghetti in a large saucepan of boiling salted water until al dente (3-4 minutes), drain and serve hot tossed with sugo and scattered with Parmigiano-Reggiano.
This recipe is from the August 2010 issue of Australian Gourmet Traveller.