Combine all the ingredients except the olive oil, salt, and pepper. With an immersion blender or in a blender, mix the ingredients together to form a paste. Slowly drizzle the oil into the mixture, while blending, until a thick dressing forms. Season with salt and pepper. Set aside or refrigerate until serving.
Separate the leaves of Romaine and combine in a large bowl with the anchovy fillets, Gouda, parsley, black pepper, lemon zest, and croutons (if desired). Add the Caesar dressing and toss well to coat the ingredients.
Whisk the buttermilk and mustard together in a large bowl. Place the chicken breasts in the buttermilk mixture and marinate for about 30 minutes.
Mix the bread crumbs, grated cheese, thyme, salt, and pepper in a small bowl and set aside.
Remove each chicken breast from the marinade and coat on both sides with the panko/Parmesan mixture. Heat two large saute pans until moderately hot and add half of the butter or oil to each pan. Add three chicken breasts to each pan. Cook until the chicken is golden brown and the internal temperature reaches 160ºF, about 5 minutes on each side. Remove the chicken and drain on paper towels to remove any excess oil. Serve warm.