Cheese soufflé with kale

Ingredients:

• Unsalted butter, for greasing ramekins
• 2 tablespoons extra-virgin olive oil
• 1 medium onion, chopped
• 1 package (450 g) frozen kale, thawed
• 1 cup grated cheddar (about 100 g)
• 6 large eggs
• 1.5 cups of milk

Preparation:

1. Preheat oven to 175°C. Grease ramekins with butter.
2. Heat olive oil in a large skillet over medium heat. Add the onion and cook, stirring, until golden brown, 6-8 minutes. Add the kale, 1 teaspoon of salt, and a couple of turns of black pepper and cook until the kale is tender, about 6 minutes. Divide the kale mixture evenly among the prepared ramekins. Sprinkle with cheddar.
3. Separate the egg whites from the yolks. Whisk the yolks in a large bowl with the milk and 0.5 teaspoon of salt. In a separate bowl, beat the egg whites with ¼ teaspoon of salt until soft peaks form. Then gently fold the whites into the yolk mixture.
4. Evenly distribute the beaten eggs among the molds and bake until set and puffed, 25-30 minutes. Serve the soufflé immediately.