Heat the oven to 200C/fan 180C/gas 6. Make the tomato sauce by cooking the garlic in olive oil, then adding the tinned tomatoes and basil leaves. Simmer until thickened.
Divide the sauce between two
shallow gratin dishes. Arrange overlapping rows of tomato and courgette
sprinkling some gruyère between them. Drizzle with oil, season and bake
covered with foil for 20 minutes. Remove the foil and bake for 15-20 minutes. Serve with crusty bread.