Roughly chop the cleaned and stemmed greens.
Place them in a large, dry skillet. For tender greens like spinach, the water clinging to the leaves is enough. For tougher greens like kale or collards, add 2-3 tablespoons (45 ml / 1.5 fl oz) of water.
Cover the skillet and cook over medium heat for 5-7 minutes, or until the greens are wilted but still vibrant green. Tougher greens may need a few extra minutes to become tender.
Transfer the wilted greens to a colander and gently press out as much excess water as you can with the back of a spoon. This step is key to avoiding a soggy dish!
Wipe the skillet dry and return it to medium heat.
Add the butter and olive oil.
Once the butter is melted, add the minced garlic and sauté for 2-3 minutes until fragrant and just beginning to turn golden. Be careful not to let it burn.
Add the drained greens back to the skillet.
Toss everything together to coat the greens in the garlicky oil and sauté for another 5 minutes until heated through.
Season generously with freshly ground black pepper and serve immediately.
Don't overcrowd the pan. If you're making a very large batch, it's better to wilt the greens in two separate batches to ensure they cook evenly.