Blot steaks with paper towel, coat both sides with 1/2 t of the oil and season generously with salt.
When air fryer has reached 400°F add steaks to the basket and cook for 3 minutes. Turn steaks after 3 minutes and cook for another 3 minutes. Flip again and cook for an additional 1 minute on each side for a total of 8 minutes for medium-rare, test with a meat thermometer. Check out handy steak temperature chart for more.
Turn off the air fryer. Place 1 slice of cheese on each steak and close the fryer basket to let the steaks rest and then melt the cheese for 5 minutes.
While the steaks are cooking, heat the remaining oil over medium-high heat and add the garlic. Cook for 1 minute, stirring, then add the fresh spinach.
Use tongs to toss the spinach until it begins to wilt, about 2 to 3 minutes. Turn heat to low and cook for an additional 3 minutes, season with salt and pepper. Cover pan and turn off the heat.
Divide spinach between 2 plates, add steak and drizzle with the balsamic reduction. Top with tomato heart garnish.
To make tomato hearts slice each tomato diagonally through the middle. Flip 1 piece halfway so pointed ends of tomatoes are touching, forming a heart shape. Place a toothpick through the center of the heart to hold both pieces in place. Marvel at how adorable they are.