Preheat the oven to 400 degrees.
Place the cloves of garlic in the center of a square of foil. Drizzle with about 1 tsp. olive oil and seal the foil tightly around the garlic. Place the foil packet in the oven and roast until the garlic becomes very soft, 35 minutes. Remove the foil packet from the oven and open it carefully. Allow the garlic to cool and then gently remove the peels.
In the bowl of a food processor, combine the roasted garlic, white beans, lemon juice, rosemary, olive oil, and sea salt. Pulse several times until the beans become uniformly smooth and creamy. Taste and add additional salt, if needed.
Brush each of the baguette slices with olive oil and toast under the oven's broiler, or (as in the image above) in a large skillet over medium heat. Top each of the toasted baguette slices with a generous spoonful of white bean puree and set out on a plate. Top with sliced basil and drizzle with olive oil. Serve immediately.