Preheat the oven to its maximum temperature (you could also use the grill).
Stab the meat of the tomatoes repeatedly until some of it starts to loosen.
Place them on a tray and squeeze a quarter of the butter down onto each one.
Season with salt and pepper and pop them into the oven for 10 minutes or until brown on the edges.
While the tomatoes are roasting, mix the pesto/basil, the nuts and the cheese together.
When the tomatoes are done, pour the juice from the tray into the crust mixture and mix.
Pack the crust mixture on top of each tomato and place back in the oven for another 5 minutes are so. They should go a beautiful golden brown.