Combine shallots, butter, vinegar, thyme, salt, and rind, stirring well with a whisk.
Preheat oven to 450°.
Snap off tough ends of asparagus. Arrange asparagus in a single layer on a jelly roll pan coated with cooking spray. Cover with foil; bake at 450° for 5 minutes. Uncover and bake an additional 10 minutes or until asparagus is crisp-tender. Pour butter mixture over asparagus, toss gently to coat. Serve immediately.