6 cups cubed (1-inch) Yukon gold potatoes
3 1/2 cups panko, divided
1 large egg, lightly beaten
1/2 cup shredded Cheddar
1/2 cup cooked and crumbled bacon
1/2 cup chopped green onion
1/4 cup butter
1/4 cup sour cream
1 clove garlic, minced
1 teaspoon salt
1/2 teaspoon ground black pepper
3 tablespoons extra-virgin olive oil