1. Bring large pot of salted water to rolling boil over high heat. Add elbow macaroni and cook according to package directions until al dente, typically 7-8 minutes. Drain in colander and set aside. Do not rinse.

2. While pasta cooks, cut steak into ½-inch cubes, trimming away large pieces of fat. Pat steak pieces dry with paper towels. Season generously on all sides with salt and black pepper.

3. Heat olive oil in large skillet over medium-high heat until shimmering. Add seasoned steak cubes in single layer without crowding. Sear 2-3 minutes on each side until nicely browned and cooked to medium-rare. Remove steak from skillet and set aside on plate.

4. In same skillet with steak drippings, add diced bell peppers and onions. Reduce heat to medium and sauté 4-5 minutes, stirring occasionally, until vegetables are softened and slightly caramelized on edges.

5. Reduce heat to medium-low. Pour whole milk into skillet with vegetables, stirring to scrape up browned bits from bottom. Let milk warm about 1 minute until hot but not boiling—you should see gentle steam rising.

6. Add garlic powder and onion powder to warm milk, stirring to combine. Add shredded pepper jack cheese gradually, about ½ cup at a time, stirring constantly in figure-eight pattern. Wait for each addition to mostly melt before adding more.

7. Taste cheese sauce and season with additional salt and pepper as needed. If sauce seems too thick, add splash more milk and stir. If too thin, let simmer 1-2 minutes to reduce slightly.

8. Add cooked steak and drained macaroni to skillet with cheese sauce and vegetables. Using large spoon or spatula, gently fold everything together until pasta is completely coated and steak and veggies are evenly distributed.

9. Let mixture sit over low heat 1-2 minutes to heat through and allow flavors to meld. Give final taste test and adjust seasoning if needed.

10. Transfer to serving bowls. Garnish generously with chopped green onions. Serve immediately while hot and cheese is at its meltiest.