In a bowl, add carrot slices, lemon juice and pepper. Toss to combine. Allow it to marinate for 15 minutes.
Add cream cheese, garlic, parsley, butter, salt and pepper to a blender. Pulse until combined.
Cut the loaf in half. Spread garlic cream cheese spread generously on both the sides of the loaf.
On the bottom slice of the loaf, add a layer of carrots, then tomatoes and ending with the onion slices. On the other half of the loaf add a layer of cheese slices.
Place the cheese side down and gently press the sandwich. Cut it in half. Serve immediately or wrap it with parchment paper and pack it in your lunch box.