Heat a large skillet over medium-high heat. Add the butter and oil, melting and combining them for 1-2 minutes. Look for bubbling to indicate readiness.

Add the chopped onion to the skillet, sauté for about 3 minutes until translucent. Stir occasionally.

Incorporate the thinly sliced cabbage into the skillet, stirring to coat. Sauté for 4-5 minutes until softened and edges start to caramelize.

Stir in the chopped kale and minced garlic, seasoning with salt, pepper, and chili flakes. Cook for another 8-10 minutes, stirring frequently.

Pour in the vegetable stock, scraping the caramelized bits from the pan. Cook for an additional 2 minutes to reduce.

After the liquid has evaporated to your liking, adjust seasoning as needed, then sprinkle with fresh parsley and serve immediately.