Start by making the breadcrumb topping. Heat the butter in a medium skillet over medium heat. When the butter is melted and bubbling, add the garlic and cook just until golden, about 1-2 minutes. (Keep a very close eye on it, it goes from golden to brown quickly!) Add the breadcrumbs and a tiny pinch of salt and stir to coat them with butter. Immediately transfer the breadcrumbs to a bowl and set aside.
Add the cream, lemon zest, thyme, kosher salt and black pepper to a bowl and whisk to combine. Fold in ½ cup of the Austrian Mountain cheese.
Assemble the gratin. Place the asparagus in a medium baking dish (I like a 9” x 11” or9” x 13”) in an even layer. Pour the cream mixture on top of the asparagus and toss to evenly distribute. Sprinkle the asparagus with the remaining ½ cup Austrian Mountain cheese and the garlicky breadcrumbs.
Bake for 13-15 minutes until the asparagus is tender and the cheese is melted and bubbling. Top with extra fresh thyme if you’d like and serve immediately.