Preheat oven to 350°F. Butter a 2-quart baking dish.
Place peeled garlic on a sheet of aluminum foil, coat with 2 tablespoons olive oil, and wrap tightly. Roast for 20 minutes, or until golden. Remove from foil, mash, and set aside.
Place sweet potatoes in a pot of water and bring to a boil. Cook for 6 minutes, or until fork tender.
In a skillet over medium heat, warm 1 tablespoon olive oil. Add sweet potatoes and cook until caramelized. Remove from skillet and dice into cubes.
Bring a large pot of water to a boil and add macaroni. Cook for 8 minutes, stirring often. Drain, then set pasta aside.
In the same pot, melt butter over low heat. Add flour, stirring constantly for 3 minutes. Add salt and pepper and whisk in half-and-half. Increase heat to medium and allow mixture to boil. Turn off heat and add 1-3⁄4 cups Italian blend cheese and 1⁄2 cup Asiago cheese. Whisk until smooth, then add mashed garlic, sweet potatoes, rosemary, minced garlic, and pasta. Stir to combine, then pour into prepared baking dish.
In a bowl, combine bread crumbs with remaining cheeses and olive oil. Sprinkle over macaroni mixture and bake for 25 to 30 minutes, or until bubbling and golden brown.