While the tomatoes are roasting. Cut the cauliflower into florets and place into a food processor. Blitz up the cauliflower (you may have to do this in batches, depending on how big your food processor is!) Place the blitzed up cauliflower in a microwave proof bowl and cook in the microwave for 5 minutes. Once cooked, pour the cauliflower onto a clean tea towel and leave to cool for approximately 15 minutes. Once cooled, wrap the tea towel around the cauliflower and squeeze out all the water. There will be lots and lots. Please make sure the cauliflower is cool otherwise you will get burnt! Place the dried out cauliflower in a clean bowl and add the Parmesan cheese, egg and mixed dried herbs, with a little salt and pepper and mix with a wooden spoon until combined. Tip the "dough" into the flan tin and using your fingers press the cauliflower mix around the tin to form a crust, make sure you get it as even as possible and press up the sides. Place the flan tin in the oven and cook for approximately 10-15 minutes until it starts to turn golden. The crust should feel firm.