2. Add kale to boiling water and cook 10 seconds. Using a slotted spoon, transfer kale to ice water. Once cool (after 10 to 20 seconds), transfer kale to colander to drain.
3. Heat oil in a large skillet or Dutch oven over medium heat. Add pancetta and cook until golden, 2 minutes. Stir in chili flakes and garlic. Cook, stirring constantly, until garlic is golden, 1 to 2 minutes.
4. Add kale all at once and toss to combine. Stir in ¼ teaspoon salt. Cook 6 to 8 minutes, stirring occasionally, until heated through and kale is tender-crisp. Transfer to a serving platter and top with cheese.