For garlic butter, combine softened butter and margarine in a food processor and whip continuously, while adding all other ingredients except for the egg yolk. Continue processing for 3 minutes, until all ingredients are combined and mixture is light and airy. Add the egg yolk and adjust seasoning with salt and pepper. Process for 30 seconds more. Transfer butter mixture to a small bowl and set aside.
Rinse and drain snails, then pat dry.
For glaze, melt butter in a sauté pan over medium heat, and sauté garlic and shallots for 3 minutes. Add herbs, beef stock, red wine and brandy and simmer 5 to 7 minutes until reduced to a glaze consistency. Add snails and sauté for 2 minutes or until they are heated through. Adjust seasoning with salt and pepper. Remove from heat and let cool.
Preheat oven to 400°F.
Transfer snails to snail plate. Cover snails completely with butter mixture.
Bake for 5 minutes or until snails are hot and butter is completely melted and brown on top. Serve immediately with slices of freshly baked bread.
The original recipe calls for 1 tablespoon of veal demi-glace but I used beef stock instead.