Preheat the oven to 400°F (200°C). Spray a sheet pan with cooking spray and set it aside.
In a small bowl, whisk together 1/3 cup olive oil, zest of 1 lemon, juice of 1 lemon, 3 cloves minced garlic, 2 tablespoons chopped parsley, 1 teaspoon chopped rosemary, 1 teaspoon salt, and 1/2 teaspoon ground pepper.
Cut 2 1/2 pounds Yukon potatoes into 1-inch pieces.
Place the cut potatoes in a large bowl, pour the olive oil–lemon mixture over them, and toss until all pieces are evenly coated.
Spread the coated potatoes in a single layer on the prepared sheet pan.
Roast in the preheated oven for 40–45 minutes, stirring once about halfway through, until the potatoes are golden and tender when pierced with a fork.
Remove from the oven and serve warm.