Heat oven to 425°F. Coat 18x13-inch rimmed baking sheet with a little additional oil.
In large bowl, mix 2-3 tablespoons of the olive oil, 1/2 teaspoon of the teaspoon salt, 1/4 teaspoon of the pepper and 1 tablespoon of fresh rosemary. Add potatoes and toss to coat. Place potatoes on the pan in a single layer. Roast 20-25 minutes or until potatoes start to brown and are tender when pierced with a fork.
While potatoes are cooking mix 2 tablespoons olive oil, 1/2 teaspoon salt, 1/4 teaspoon pepper and 1 tablespoon fresh rosemary in the same bowl used for the potatoes. Add chicken and toss to coat.
In a smaller, separate bowl add 1 tablespoon oil, prepared asparagus, and 1 teaspoon minced garlic.
When the potatoes have started to brown and are tender, stir them on the baking sheet and place chicken pieces on the sheet. Roast potatoes and chicken for about 12 minutes, then open the oven and arrange asparagus on top. Roast an additional 6-10 minutes longer or until juice of chicken is clear when center of thickest part is cut (or internal temperature reads at least 165°F with an instant read thermometer) and potatoes are nicely browned.
Squeeze lemon over dish and serve!