Combine chili powder, thyme, smoked paprika, oregano, cayenne pepper, cumin, onion powder, and salt in a bowl.

Melt butter in a large skillet over medium heat; cook and stir onion in hot butter until translucent, about 5 minutes. Add garlic and cook until soft, about 2 minutes; stir shredded cabbage into onion and garlic. Cook and stir cabbage mixture until cabbage starts to soften, about 5 more minutes.

Stir spices into cabbage mixture and cook, stirring often, until spices are evenly mixed in and cabbage is tender, 3 more minutes.