To cook asparagus in the oven, the general guideline is to roast it at around 400-425°F (204-220°C) for about 10 to 15 minutes. The exact time depends on the thickness of the asparagus stalks:

• Thin stalks (about 1/4 inch thick or less): Roast for 8-11 minutes.
• Medium stalks (3/8 to 4/8 inch thick): Roast for 12-15 minutes.
• Thick stalks (5/8 inch or thicker): Roast for 16-20 minutes.

You want the asparagus to be tender but still have a slight bite, with some browning on the tips for flavor. It is best to spread the asparagus in a single layer on a baking sheet, drizzle with olive oil, and season with salt and pepper before roasting. Avoid crowding the pan to prevent steaming instead of roasting. For example, roasting at 425°F for 12-15 minutes is common for average thickness asparagus, resulting in tender, flavorful spears

. Summary:

Thickness| Temperature| Time
---|---|---
Thin (≤1/4")| 400-425°F| 8-11 minutes
Medium (3/8"-4/8")| 400-425°F| 12-15 minutes
Thick (≥5/8")| 400-425°F| 16-20 minutes

This method yields crisp-tender asparagus with a pleasant roasted flavor