In a large bowl, mix together the cheeses. In another medium-sized bowl, mix together the mayonnaise, sour cream, and herb paste.

Mix the butter and garlic together in a small bowl and then add to the mayonnaise mixture. Add the mayonnaise/butter mixture now to the cheese.

Preheat the oven broiler, and slice a loaf of bread in half horizontally. Place crust side down on a rimmed baking sheet. You can cover the pan with either parchment paper or aluminum foil for easy cleaning.

Divide the cheese mixture between the two halves and spread to cover.

Broil until cheese is melted and starts to get golden brown. Let sit for a minute, then slice and serve immediately.