Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add chicken cubes in a single layer and cook undisturbed for 3 minutes until golden on one side, then flip and cook 2 minutes more until no longer pink inside.

Remove chicken to a plate and add 1 tablespoon butter to the same pan. Toss in diced onion and cook for 2 minutes until softened, scraping up browned bits from the bottom.

Add gnocchi and ¾ cup chicken broth, then bring to a simmer. Cover and cook for 4 minutes until gnocchi puffs and softens, stirring once halfway through.

Stir in 1 cup heavy cream, minced garlic, and fresh thyme leaves. Simmer uncovered for 3 minutes until the sauce thickens enough to coat the back of a spoon.

Return chicken to the pan and stir in ½ cup grated Parmesan. Cook for 1 minute until cheese melts and everything is heated through, then remove from heat and let rest 2 minutes before serving.