Preheat the oven to broil. Line a baking tray with foil paper.
Cut half of a baguette lengthwise to expose the bread, cut each half into thirds. You’ll have 6 open faced pieces.
Spread 1 Tablespoon of butter on each piece of bread and place on foil lined baking tray. Sprinkle each piece with garlic powder and parsley to taste.
Broil until browned, about 2-3 minutes.
Add 1 Tablespoon of onion jam (or to taste), 1 Tablespoon of horseradish (or to taste), and 2 teaspoons mustard (or to taste). Add a couple of slices of roast beef and serve.