In a medium bowl, combine the softened cream cheese, chopped roasted red peppers, minced onion, and garlic.
Mix until well combined.
Cut each 18-inch baguette into three 6-inch pieces.
Slice each piece in half lengthwise. Gently scoop out some of the soft bread from the center of each half to create a hollow for the filling.
Generously spread the roasted red pepper cream cheese mixture onto the bottom half of each baguette piece.
Layer with diced cucumber, romaine lettuce, and radicchio.
Place the top half of the baguette on top to complete the sandwich.