Heat half the olive oil in a saucepan that has a tight-fitting lid over a medium heat. Add the sliced garlic and courgettes and ½ tsp of salt. Stir, increase the heat to full and leave for 5 minutes, stirring occasionally.
Place the lid on the pan, reduce the heat to medium, and cook for 10 minutes, until the courgettes are caramelized and a bit mushy. Remove the lid and cook for a further 5 minutes.
Tear half the basil leaves into rough pieces and stir them into the courgettes. Check the seasoning, adding black pepper as needed. Set aside. Take the four slices of toast and rub with the halved garlic clove. Place the toast on a serving plate.
Place the chopped olives in a bowl. Finely chop the remaining basil leaves and stir them through the olives with the lemon juice and remaining olive oil, to form a paste. Spread the paste equally over the slices of toast and divide the cooked courgettes on top. Scatter over the dressed rocket leaves and finish with shavings of ricotta salata.