Bring a large pot of salted water to a boil. Add the elbow macaroni and cook according to package instructions until al dente, about 7-8 minutes. Drain the pasta and set aside.
While the pasta cooks, heat the olive oil in a large skillet over medium-high heat. Season the steak pieces generously with salt and pepper. Add them to the skillet and cook until browned on all sides, about 3-4 minutes. Remove the steak from the skillet and set aside.
In the same skillet, reduce heat to medium. Melt the butter, then whisk in the flour, garlic powder, onion powder, and paprika to form a smooth roux. Cook for 1-2 minutes, whisking constantly, until the mixture is golden and bubbly.
Gradually whisk in the milk, ensuring no lumps form. Continue whisking until the sauce thickens, about 4-5 minutes. Remove the skillet from heat and stir in the shredded cheddar and Monterey Jack cheese until melted and creamy.
Add the cooked macaroni, seared steak pieces, and diced green chiles to the cheese sauce. Stir gently to combine everything evenly. Taste and adjust salt and pepper if needed.
Scoop the mac and cheese into bowls or plates and serve hot. For an extra indulgent touch, you can broil the top with a sprinkle of extra cheese until golden and bubbly.