Cover the salt cod in cold water and leave to soak for 12 hours, changing the water as often as possible.
Place the soaked salt cod in a saucepan and cover with fresh cold water. Bring to the boil, then reduce the heat and simmer for 5 minutes. Drain. When cool enough to handle, flake the fish into a food processor, removing the bones and skin. Add the garlic and blend. While the motor is running, pour in the cream. Remove from the processor and season with paprika, lemon juice and pepper. Salt will most likely not be needed. Place the pâté in a bowl and cover with clingfilm. Once cool, place in the refrigerator for at least 1 hour.
Make the crostini by stamping out 4 x 3 cm (1¼ inch) rounds from each slice of bread using a biscuit or pastry cutter. Place them on a baking sheet, drizzle with a little olive oil and cook for 7–10 minutes in a preheated oven, 180°C (350°F), Gas Mark 4, until golden and crispy.
Spread the salt cod pâté on the crostini and sprinkle with finely chopped chives, if liked.