Preheat oven to 400 and line a baking sheet with parchment paper.: You will smell the oven warming as it approaches 400 degrees, and that initial heat is what sets the stage for blistering and browning. Using parchment creates a nonstick surface that makes turning and removing vegetables easier, and it also prevents excessive sticking that can tear delicate asparagus. A common mistake is not preheating fully, which leads to longer cooking and less crispness, so wait until the oven reaches temperature before sliding the pan in.
Place potatoes in a mixing bowl with garlic and 2 tablespoons olive oil. Mix well to evenly coat.: As you toss the chopped potatoes with minced garlic and 2 tablespoons olive oil , you should notice the oil glossing each piece and the garlic beginning to cling to the skin. This coating encourages even browning and infuses the interior with savory aroma as the potatoes roast. Avoid undercoating, which can produce dry, pale potatoes, and also avoid overmixing which can bruise them.
Break the ends off of the fresh asparagus and discard. Place asparagus on baking sheet and drizzle with remaining 2 tablespoons olive oil. Use your hands to mix the asparagus and coat evenly. Spread asparagus in a single layer on the baking sheet. Add potatoes to baking sheet, keeping in a single layer.: When you snap the woody ends from the asparagus , listen for the crisp break, a good sign of freshness. Rubbing the oil into the stalks by hand warms them slightly, helping the oil adhere and promoting more even roasting. Laying vegetables in a single layer avoids steaming, and spreading them gives each piece room to brown. Overcrowding the pan frequently causes soggy results, so if your pan feels packed, use a second sheet.
Sprinkle with salt and pepper.: As the scent of olive oil and garlic mingles on the pan, a measured dusting of salt and pepper sharpens those aromas and helps the surface moisture draw out, which assists browning. Seasoning before roasting also seasons the interior as the vegetables release steam. A common mistake is waiting to salt until after cooking, which can result in flatter flavor and less integrated seasoning.
Roast vegetables for 20 minutes. Check the doneness of the potatoes and if necessary continue to roast for 2-5 minutes or until tender. Remove from oven and serve with shredded cheese.: Around the 20 minute mark the kitchen will fill with a toasty, nutty scent, and you should see golden edges on the potatoes and slight char on the tips of the asparagus . Test a potato piece with a fork for tenderness, it should pierce easily and reveal a fluffy interior. If they need a few more minutes, continue watching closely to avoid drying out the asparagus. A frequent error is leaving them too long, which can make the asparagus limp and the potatoes dry, so err on the side of checking early.