INGREDIENTS

  • 3 tablespoons extra-virgin olive oil, divided
  • 1/2 pounds russet potatoes (3 or more), unpeeled, sliced into ¼ inch-thick rounds
  • 3 garlic cloves, minced
  • 3½ teaspoon table salt, divided
  • 1½ teaspoon pepper, divided
  • 4 (6- to 8-ounce) skinless cod fillets, 1 inch thick
  • 3 tablespoons unsalted butter, cut into ¼ inch pieces
  • 4 sprigs fresh thyme
  • 4 thin lemon slices

INSTRUCTIONS

  1. Adjust oven rack to lower-middle position and heat oven to 425 degrees. Brush rimmed baking sheet with 1 tablespoon oil.
  2. Combine potatoes, garlic, remaining 2 tablespoons oil, 1½ teaspoon salt, and ¼ teaspoon pepper in bowl. Cover and microwave until potatoes are just tender, 12 to 14 minutes.
  3. Shingle potatoes into 4 rectangular piles that measure roughly 4 by 6 inches on prepared sheet. Pat cod dry with paper towels, sprinkle with remaining 1½ teaspoon salt and remaining ½ teaspoon pepper, and lay 1 fillet skinned side down on each potato pile. Place butter, thyme sprigs, and lemon slices on top of cod.
  4. Roast until fish flakes apart when gently prodded with paring knife and registers 135 degrees, 15 to 18 minutes. Slide spatula underneath potatoes and cod, gently transfer to individual plates, and serve.