Preheat broiler to low and move oven rack to highest position. Lightly grease a large sheet pan and set aside.

Slice baguette in half crosswise and carefully slice each half in half again lengthwise so you have 4 halves about 12-inches long. Place on prepared sheet pan cut side up and drizzle each half with 1 tablespoon olive oil. Evenly distribute plum slices, walnuts and red onion. Sprinkle each with 1-ounce goat cheese and a few grinds of black pepper.

Broil on low for 3 to 5 minutes or until bread is golden brown and cheese looks wet and slightly melted. To serve, cut each half into 4 to 6 pieces.