In a large skillet, heat 2 tablespoons of unsalted butter and 1 tablespoon of olive oil over medium-high heat until sizzling. Carefully place the cabbage wedges in the skillet, flat side down. Sear for about 3 to 4 minutes until they turn golden brown and slightly caramelized. Flip the cabbage wedges and sear the other side for another 3 minutes. Remove them from the skillet and set aside.

Reduce the heat to medium and add a chopped yellow onion to the same skillet, stirring occasionally. Cook for about 5 minutes, allowing the onions to soften and become golden.

Stir in 3 minced garlic cloves and 1 teaspoon of Cajun seasoning to the onions, cooking for an additional minute.

Pour in 1 cup of heavy cream, gently scraping the skillet to incorporate any browned bits. Simmer over medium heat for about 2 to 3 minutes until it thickens slightly.

Sprinkle in 1 cup of freshly grated Parmesan cheese, stirring until it melts and combines smoothly with the sauce. Return the seared cabbage to the skillet and spoon the sauce over the wedges. Partially cover and cook for another 5 minutes.

Remove from heat, garnish with freshly chopped parsley, and serve warm.