Prepare all ingredients as listed. Remove the Brie from the refrigerator and allow it to sit briefly to soften slightly.
Optional: toast the baguette.
In a bowl, combine the butter, chives, parsley, Dijon mustard, and garlic. Mix until smooth and well combined. Season with salt and black pepper.
In a bowl, toss the arugula with lemon juice, salt, and black pepper until lightly coated.
Spread the herb butter evenly inside the baguette. Layer with deli ham, Brie, and dressed arugula.
Combine the sparkling water, lemon slices, and chia seeds. Stir well and allow the chia seeds to hydrate briefly.
Serve the sandwich with carrots, hummus, and lemon chia sparkling water.