Preheat the oven to 400F / 200C / 180C Fan.

Arrange the tomato halves over two half sheet pans lined with parchment paper. Drizzle with olive oil, salt and pepper. Slice the top off of the garlic to get all of the cloves exposed, then place it facing down on the pan too (with a little olive oil underneath).

Place in the oven for around 50-60 minutes, until the tomatoes have reduced and are browning around the edges. Remove from the oven and set aside for about 10 minutes to cool down.

In a wide bottomed pan, melt the butter over a low heat with the two crushed garlic cloves, just until the garlic scent hits the air, then remove from the heat and set aside.

Now, one by one, cut off the stems of the roasted tomatoes and peel off the skins (they should come away easily). Add them to the pan with the garlic butter. Squeeze the garlic head to get all of the roasted garlic out of each clove. Then make sure to pour any juices from the roasting pans into the pan too.

Place the pan back on the heat, stir through, and use a potato masher or the back of a wooden spoon to start to gently mash and break up the tomatoes.

Add the sugar and vinegar, then let the sauce cook, with the lid cracked, over a low heat for about 1 hour. Lift the lid regularly to stir and continue to break up the tomatoes. Eventually you will have a thick but chunky sauce. If you are finding it stays too watery, just simmer with the lid completely off for a while. If you prefer a smooth sauce, feel free to puree all or some of it with a hand blender or in a jug blender (though if you're using a jug blender, you need to allow it to cool down before blending).

Add the fresh basil and stir through.

Serve immediately.