1. Preheat oven to 425 degrees. Grease six 6-ounce(170-gram) ramekins well with cooking spray.
2. In a small saucepan, melt together white chocolate and margarine over medium heat, stirring until smooth.
3. In a large bowl, whisk together eggs and egg yolk until foamy. Add sugar and mix well to combine. Add the salt, vanilla, liqueur, and white chocolate mixture, mixing until very smooth. Blend in the flour, mixing until no streaks remain.
4. Divide batter evenly among prepared ramekins. Bake for 16–18 minutes, until the tops of the soufflés are golden and feel slightly firm to the touch. Remove cakes from oven and prepare to serve immediately.