Heat the oven to 375°F and grease a 2-quart baking dish. Cook macaroni in a large pot of water with the tablespoon salt until 1 minute short of the package time, then drain.
While the pasta cooks, melt the sauce butter in a saucepan. Cook diced jalapenos over medium heat for 4 minutes, then add garlic for 30 seconds.
Add milk and cream cheese and stir over low heat until smooth. Remove from the heat and fold in Monterey Jack, sauce salt and pepper.
Fold in macaroni and transfer to the dish. Toss panko with topping butter and scatter in a thin layer over the pasta.
Bake for 20 to 25 minutes until bubbling and golden on top. Rest for 5 minutes before serving.