Preheat your pellet grill to 375-400 °F.
Fold up a little foil tray with raised sides. Or use a small baking pan with sides that is secure.
Cut off the tough ends of the asparagus, and wash well. Let dry, and then toss with olive oil.
Sprinkle the seasonings evenly on the asparagus, and lay in a single layer on a foil tray or baking tray.
Top with pats of butter, and grill over medium heat until the asparagus is tender-crisp, about 6-8 minutes.
Toss lightly in the butter that has melted at the bottom of the tray, and serve immediately.