For the roasted garlic skinny dip, preheat the oven to 220C/425F/Gas 7 (fan 200C). Drizzle the oil in the centre of a 20cm/8in square of aluminium foil and sit the garlic, cut-side down on top. Wrap up loosely, sit on a small baking tray and pop in the oven straight away (even if the oven is not hot enough) to cook for about 50-55 minutes, or until very soft.
For the marinara sauce, heat the oil in a medium pan over a low heat. Add the onion and cook for about 6-8 minutes, or until beginning to soften, stirring regularly. Add the garlic and cook for a further minute. Stir the tomatoes, thyme, sugar (if you think it needs a little sweetening) and some salt and pepper. Turn down the heat so that the mixture is just simmering and leave to cook for 15-20 minutes, or until the sauce has thickened and the flavours have intensified.
Meanwhile, make the courgette fritters. Line two large baking trays with baking parchment. Beat the eggs in a large shallow bowl. Put the flour into another and stir in a couple of large pinches of salt and lots of pepper. Divide the breadcrumbs, parmesan and rosemary evenly between two large shallow bowls and set aside.
Trim the courgette ends and slice one lengthways into three evenly-sized slices. Cut each slice into three long, evenly-sized strips and then in half across their width to give 18 chips. Repeat with the second courgette to give 36 chips in total. Each one will be about 1.5cm/¾in wide and 7-8cm/3in long, depending on the size of your courgettes.
Working with a few at a time, toss the courgette batons in the flour until well coated - this will help the egg to stick in the next stage. Toss through the beaten egg and, after allowing the excess egg to drip off, roll them around in one of the batches of breadcrumbs to stick all over evenly. Arrange in a single layer on the baking trays as you go. Repeat until all of the courgettes are coated, using the second batch of breadcrumbs once the first has been used up.
The marinara sauce will probably be nice and thick at this stage. If it's too thick to pour, stir in a little water. Remove from the heat, season to taste with salt and pepper, add the basil leaves and cover to keep warm until ready to serve.
Spray the courgettes with the oil and place in the oven for 20 minutes. If tight on space, nestle the garlic parcel onto one of the courgette trays. Half way through cooking time, remove the courgettes, turn them over, give another spray and pop them back in the oven - this time on the opposite shelves to what they were already on. Once cooked, they should be lightly browned and very crisp all over.
Once softened, remove the garlic from the oven and, when cool enough to handle, unwrap it and squeeze the garlic cloves from their papery skins into a bowl. Mash lightly with a fork and then add the cream cheese, yoghurt and chives and stir everything together really well. Season to taste and spoon into a serving bowl.
Spoon the marinara sauce in a serving bowl. Pile the courgettes onto a serving platter and serve with the lemon wedges.