To roast the garlic, remove the outer papery skin from the bulb. Leave the skin on the garlic clove. Slice off one end of the garlic. Rub olive oil on the exposed end and wrap in foil. Place on a baking tray and roast for 20 mins at 200°C / 180°C fan / gas 6.
Place the cashews on a baking tray and roast at 200°C / 180°C fan / gas 6 until a dark golden brown, approximately 7 minutes.
Make a start on preparing the tomato mixture. Remove the stems from the tomatoes. Dice the tomatoes and then place in a colander and drain well.
Add the tomatoes to a bowl along with the remaining ingredients. Season generously with salt and pepper.
Remove the garlic from the oven and allow to cool for a few minutes. Then carefully peel the skin from the garlic. Scrape out the buttery garlic and add to a food processor along with the roasted cashews, fresh basil leaves, olive oil, lemon and nutritional yeast. Season generously with salt and pepper. Blend well, scraping the sides of the blender as necessary.
Serve the pesto on warm toasted bread, spoon on the tomatoes and garnish with fresh basil leaves.