Smoked Salmon Cake

Name: Smoked Salmon Cake
Ingredients: 3 eight-ounce packages cream cheese, softened; 1/2 cup finely chopped red onion; 2 tablespoons capers, drained and chopped; 2 tablespoons fresh dill, finely chopped, plus more for garnish; 1 teaspoon freshly squeezed lemon juice; Coarse salt and freshly ground pepper; 2 loaves pumpernickel bread, cut into 16 half-inch slices, with crusts; 1 pound smoked salmon, thinly sliced; 1 1/2 seedless cucumbers, thinly sliced into 1/8-inch slices, patted dry, plus more for decorating sides of cake; 1/2 cup creme fraiche; 2 1/2 ounces salmon roe; 1 ounce black caviar; Lemon wedges, for garnish