Step 1

Arrange a rack in the middle of the oven and heat the oven to 425°F. Line a baking sheet with parchment paper.

Step 2

Cut 1 pound Jerusalem artichokes in half lengthwise; cut any very large ones in half again crosswise. Transfer to a large bowl. Add 2 tablespoons olive oil, 1/2 teaspoon kosher salt, 1/4 teaspoon garlic powder, and 1/4 teaspoon black pepper, and toss to combine.

Step 3

Transfer to the baking sheet and arrange in an even layer. Scatter 2 to 3 fresh rosemary sprigs on top. Roast, tossing halfway through, until golden brown and tender, 25 to 35 minutes total. Discard the rosemary sprigs before serving.