In a large skillet, put in the olive oil to coat pan, add asparagus and onion to heated skillet. Salt and pepper to taste. Saute just until tender. Let cool.
Spray a 11x8 jellyroll pan with cooking spray, unroll the crescent rolls and pat down to the edges of the pan for a crust. Spread the softened butter over the crust. Sprinkle the garlic powder evenly over the butter.
Evenly put the asparagus and onion on the prepared crust. Cover with the shredded swiss cheese. Bake in preheated oven 10-15 minutes until cheese is bubbly. Cut in squares, best eaten warm. Great appetizer or light lunch.