Add the asparagus to the baking sheet. Pour over the melted butter and sprinkle with the garlic, parmesan cheese, lemon juice, salt and pepper. Toss to coat the asparagus. Lay the slices of lemon on top.
Roast in the oven for 8 – 10 minutes, depending on the thickness of the asparagus, until the asparagus is tender, but not mushy.