Pat steak cubes thoroughly dry with paper towels. Season evenly with garlic powder, smoked paprika, kosher salt, and coarse black pepper.

Heat 1 tablespoon olive oil and 1 tablespoon butter in a large 12-inch heavy skillet or cast iron pan over high heat until smoking hot. Add steak bites in a single layer without crowding and sear undisturbed for 2 minutes to form a deep caramelized crust. Stir and sear for 1 additional minute until medium-rare. Immediately transfer steak bites to a warm plate.

Reduce skillet heat to medium. Melt the remaining 1 tablespoon of butter, add minced garlic and chopped fresh rosemary, and sauté for 60 seconds until fragrant.

Pour in the beef bone broth and heavy cream, scraping up all the savory browned fond from the steak. Bring liquid to a gentle simmer.

Add the fresh cheese tortellini directly into the simmering sauce. Cover with a lid and cook on medium-low for 3 to 4 minutes until the tortellini are tender and pillowy.

Remove the lid, lower heat to low, and stir in freshly grated Parmesan cheese and baby spinach. Stir for 1 to 2 minutes until spinach is gently wilted into the velvety cream sauce.

Return the seared steak bites and any flavorful resting juices back into the skillet. Toss gently for 1 minute just to re-warm steak through without overcooking.

Garnish generously with fresh flat-leaf parsley and freshly ground black pepper. Serve warm immediately.