Preheat oven to 350°F (175°C)
Pat skirt steak dry, season generously with coarse salt and black pepper
Heat 2 tbsp of garlic butter in oven-safe skillet over high heat. Sear steak for 4-5 minutes per side until deeply charred and medium-rare. Remove from pan and let rest for 5 minutes, then slice into strips
Bring a large pot of well-salted water to a boil. Cook pasta to al dente according to package instructions, then drain and set aside
In the same skillet, sauté 2 tbsp of garlic butter over medium heat. Stir in chili powder, chipotle puree, and cumin. Cook for 2 minutes until fragrant
Add half of the grated pepper jack to the pan; whisk until melted into a smooth sauce. Add salsa verde and remaining cheese to create a thick, stretchy queso
Pour cooked pasta into the queso mixture and toss well to coat
Fold in seared steak slices and any juices
Transfer pasta and steak mixture to a baking dish. Garnish with a thin layer of remaining cheese
Bake for 20 minutes until golden and bubbly on top
Let stand 10 minutes before serving