In a mixing bowl, combine finely chopped chives, fresh tarragon, minced garlic, and baby spinach. If using anchovy paste, add a small amount for extra flavor. Stir in three tablespoons of mayonnaise until the mixture is smooth and vibrant green, ensuring all ingredients are well incorporated to create your flavorful Green Goddess spread.

In a separate bowl, blend softened salted butter with the remaining mayonnaise to create a rich butter mixture. This will not only enhance the flavor of your Green Goddess Sandwich but also add a creamy touch to the bread. Mix until well combined, resulting in a smooth, spreadable consistency.

Take two thick slices of French or white bread and spread the buttery mixture generously on one side of each slice. On the other side, spread a layer of the zesty Green Goddess spread, followed by layers of low-moisture mozzarella, slices of ripe avocado, and crunchy asparagus spears. Top with another slice of mozzarella before closing the sandwich, ensuring a delicious filling.

Heat a skillet over medium-low heat. Carefully place the sandwich in the skillet with the buttered side facing down. Cover with a lid and cook for about 6-7 minutes, or until the bread is golden brown and crispy. Flip the sandwich halfway through to achieve an even golden crust and ensure the cheese melts beautifully.

Once the Green Goddess Sandwich is golden and the cheese is thoroughly melted, remove it from the skillet. Allow it to cool for a minute before slicing in half to reveal its gooey interior. Serve hot, ideally paired with a refreshing iced tea or alongside a light salad for a complete meal experience.