Place sweet potatoes in a large saucepan and cover with water. Bring to a boil. Cover and cook over medium heat until tender, 10 to 15 minutes. Drain well and return to the pan. Mash with a potato masher. Measure out 3 cups. (Reserve any extra for another use.)
Preheat oven to 350°F. Coat an 8-inch-square (or similar 2-quart) baking dish with cooking spray.
To prepare topping: Mix flour, brown sugar, orange juice concentrate, Extravagonzo Roasted Garlic Culinary Oil and butter in a small bowl. Blend with a fork or your fingertips until crumbly. Stir in pecans. Sprinkle over the casserole.
Bake the casserole until heated through and the top is lightly browned, 35 to 45 minutes.