1. Rinse cod under cold water. Transfer to a bowl; cover with cold water. Cover with plastic wrap; refrigerate 8 to 12 hours.

2. Drain cod, and cover with fresh water. Cover; refrigerate 8 to 12 hours.

3. Preheat oven to 400 degrees. Cut off top of each bulb to expose cloves. Place on foil. Drizzle with 1 tablespoon oil; wrap. Roast until soft, about 45 minutes. Let cool.

4. Squeeze cloves from bulbs into a bowl, and discard skins.

5. Drain cod, and transfer to a medium saucepan. Cover with cold water, and bring to a boil. Reduce heat to low; simmer 20 minutes. Drain cod, and let cool slightly. Transfer to a large bowl; flake into small pieces with a fork. Let cool.

6. Cover potato with cold water by 2 inches in a saucepan. Bring to a boil. Reduce heat; simmer until tender, about 20 minutes. Drain. When slightly cool, force through a ricer. Let cool completely.

7. Stir potato and garlic into cod. Stirring, pour in cream and 6 tablespoons oil. Season with salt and pepper.

8. Preheat oven to 400 degrees. Arrange bread slices on a rimmed baking sheet in a single layer. Brush one side of each slice with oil, and season with salt. Bake until golden brown on edges, 8 to 12 minutes. Let cool on sheet. Garnish brandade with caperberries. Serve with crostini.