Steak Au Poivre Sandwich with Creamy Au Poivre Sauce

**For the Au Poivre Sauce:**

1. Melt 2 tbsp unsalted butter in a saucepan over medium heat.
2. Sauté the minced shallot until translucent, about 1 minute.
3. Stir in 3 tbsp peppercorns.
4. Carefully pour in 1/4 cup cognac or brandy, exercising caution.
5. Add 1 cup salt-free beef stock and bring the mixture to a simmer.
6. Pour in 1 cup heavy cream, let it come to a boil, then reduce by half and simmer for about 10 minutes. Stir until well combined and the desired consistency is reached. Set aside.

**For the Steak Au Poivre Sandwich Assembly:**

1. Season the Filet Mignon generously with salt and pepper. Cook the steak to your desired doneness (e.g., medium-rare to medium, using a precision thermometer like TempSpike Plus for accuracy). Rest the steak for 5-10 minutes, then slice it against the grain.
2. If not pre-made, prepare caramelized onions and sauté fresh mushrooms.
3. Lightly toast the ciabatta bread.
4. Layer the toasted ciabatta bread with the sliced Filet Mignon, caramelized onions, sautéed mushrooms, and a generous amount of the warm Au Poivre Sauce.
5. Garnish with fresh chives before serving.