Place a large skillet over medium high heat. Add the oil or butter. Once the pan is hot or the butter has stopped foaming add the zucchini. Season them with salt and pepper. Blister the squash with brown spots on both sides.
The quicker you blister the veggies the better so keep the heat up. Don't fear the heat, hang with it, you will like the results. Once blistered on both sides add the basil. If the leaves are bigger then your ear tear them. Give the pan a toss so the veggies and the basil get to mingle. Taste a piece of zucchini and add more salt if you think it needs it and toss the veggies to distribute the salt.
Remove the zucc to a serving bowl. This is one dish that, to me anyway, is just as good room temp as hot. Quite often I find I can taste the different flavors of the squash better when it cools.