Bring pasta water to boil and grease a 9x13 casserole dish. Preheat oven to 400 degrees.
In a large dutch oven, melt butter over medium high heat. Add garlic and spices, sautéing for 1-2 minutes, careful not to burn garlic. Add flour to the butter, whisking contstantly, to form your roux. Whisk for 2-3 minutes until a paste forms.
Slowly pour in the milk, whisking constantly. Bring mixture to a simmer, and let thicken while bubbling and whisking constantly, over medium heat, about 5-7 minutes until thickened. Add grated cheeses slowly, whisking until cheese sauce is smooth, thickened and homogenous. Set aside off the heat.
Meanwhile, boil pasta according to directions of reaching al dente. Add pasta to the cheese sauce, mixing well, and transfer to prepared casserole dish, smoothing the top.
In a small bowl, combine breadcrumbs with melted butter. Distribute evenly atop Mac & Cheese then top with sliced candied jalapeños. Bake for 15-18 minutes until golden and bubbling. Serve immediately.