In a high-speed blender, combine the unsweetened creamy peanut butter, full-fat coconut milk (or heavy cream), erythritol or monk fruit sweetener, vanilla extract, and salt.

Blend on high speed until the mixture is completely smooth and creamy. Stop and scrape down the sides of the blender with a spatula as needed to ensure all ingredients are well incorporated.

Taste the mixture and adjust sweetener if desired. If the soup is too thick for your preference, add the unsweetened almond milk (or water) one tablespoon at a time, blending briefly after each addition, until the desired pourable consistency is reached.

Pour the blended soup into a large bowl or pitcher. Cover it tightly and refrigerate for at least 2-3 hours, or preferably overnight, to allow the soup to chill thoroughly and for the flavors to deepen and meld. Chilling is essential for the best texture and taste.

If using the optional chocolate garnish, gently melt the sugar-free chocolate chips with the coconut oil in a small microwave-safe bowl in 15-second intervals, stirring after each, or in a small saucepan over very low heat until smooth. Let the melted chocolate cool slightly so it's not too hot when drizzling.

Before serving, give the chilled soup a gentle whisk to ensure it's well combined. Divide evenly into four serving bowls. Drizzle with the melted chocolate, if desired, and serve immediately.