In a large skillet over medium heat, melt the butter.

Sauté the onion until slightly translucent, about 5 minutes.

Add the garlic, giving it a stir, and cook for another 1 to 2 minutes.

Add the kale to the pan a couple of handfuls at a time, stirring gently as the leaves wilt.

Cook the kale for about 10 minutes, until it is all wilted.

Season with salt and pepper and serve.