Preheat the oven to 425F / Gas 7.

Using a knife, slice off the top of the head of garlic, exposing the individual cloves.  Drizzle the exposed cloves with olive oil and a bit of salt, wrap in foil, place on a baking sheet and set aside.  Carefully slice the grape tomatoes in half and toss with some regular olive oil and salt in a roasting pan.  Place the garlic and the tomatoes in the oven.  Keep an eye on the tomatoes to make sure they don’t burn and take them out after 12-15 minutes.  Remove the garlic from the oven after 45 minutes.

Drain the canned tomatoes, reserving the liquid, and place in a saucepan on low heat with the chopped basil, some salt and pepper.  Chop the remaining garlic and saute in a small pan on medium-low heat for 2 minutes then add to the tomatoes.  Add the roasted grape tomatoes into the saucepan.

Remove the head of garlic from the foil and squeeze the cloves out of their skins.  Use a mortar and pestle to make a garlic paste and then stir it into the tomatoes.  Add a healthy splash of the extra virgin olive oil, 2 or 3 tablespoons, and stir.  Use an immersion blender, carefully, and puree the sauce.  You can use a regular blender for this step, if you prefer.  Then leave the sauce on low, stirring occasionally, for 4-5 hours.  The sauce will thicken up noticeably.   When you’re about to serve, stir in a bit more extra virgin olive oil and some of the reserved tomato juice.  Serve on pasta with freshly grated Parmesan cheese!