Heat the oven to 300°F. Set the white chocolate and oil in an 8- or 10-inch oven-safe skillet. Place the skillet in the oven just until the chocolate has melted, about 1 to 2 minutes. Stir chocolate until smooth, then return the skillet to the oven. Roast until chocolate is golden brown, 15 to 20 total, stirring every 5 minutes. (The chocolate may stiffen a bit but as long as it doesn’t burn it will be fine.) Transfer the chocolate to a medium bowl stir until slightly cooled.
Meanwhile, sprinkle the gelatin over 1 tablespoon cold water in a small bowl and let stand for 5 minutes. Bring ½ cup of the cream to a simmer in a small saucepan. Stir in the gelatin mixture, then add to the white chocolate. Stir in the salt.
Chill the mixture until it is the texture of thick caramel, about 20 minutes. Whip the remaining cream to stiff peaks. Fold whipped cream into the chilled chocolate mixture. Divide the mousse between 4 (4 oz.) ramekins. Cover and chill for at least 4 hours. Serve with raspberries, if desired.
Note: Total time includes chilling time.