Heat olive oil in a large saucepan or Dutch oven over medium heat.
Add onions and cook until soft and lightly golden, about 6 minutes.
Begin adding the greens, one-third at a time, pressing them down as they begin to wilt. Season with salt and pepper.
Reduce the heat to medium-low and cook, uncovered, until the greens are soft, about 8 minutes. Serve hot.
Source: Chef Rocco DiSpiritio for Biggest Loser