Cut the tops off each head of garlic and place them on separate squares of tin foil.Divide the olive oil and sea salt for the roasted garlic, and pour/sprinkle the top of each head of garlic with them.
Wrap each head of garlic, place them in the oven and roast them for 40 minutes at 180°C or 350°F. Then remove and allow to cool until they are cool enough to touch.
Remove the garlic cloves from the skins, mash them and set them aside.
Cut the cherry tomatoes in half.
Pick the spinach and clean it well.
Bring a 20cm or 8" pan of well-salted water to a boil and cook the pasta as per the instructions on the packet. I use 1½ teaspoons of salt in a pan this size.
Whilst the pasta is cooking, heat a 30cm or 12" saucepan over a high heat and add the olive oil for the pasta sauce.When the olive oil is hot, lay the cherry tomatoes cut side down and allow them to sear for two minutes.
Add the cleaned spinach, pour over the balsamic vinegar, add a lid and then cook for 2-3 minutes or until the spinach has wilted.
Drain the pasta reserving around 75ml (⅓ cup) of the cooking water.
Remove the lid from the spinach, add the cooked pasta and roasted garlic and give everything a stir adding as much pasta water as is required to form a nice emulsion.