In a medium bowl, stir together goat cheese, radish, celery, parsley, lemon zest and juice, salt, and pepper until well combined. Spread 1½ tablespoons goat cheese mixture each onto 4 frozen white bread slices and 4 frozen wheat bread slices. With goat cheese sides up, stack a wheat bread slice on top of a white bread slice. Top with a plain frozen white bread slice to create a triple-stack sandwich. Repeat with remaining bread slices to make a total of 4 triple-stack sandwiches.
Using a serrated bread knife, in a gentle sawing motion, trim and discard crusts from sandwiches. Cut each sandwich into 3 rectangles. Serve immediately, or cover with damp paper towels, place in a covered container, and refrigerate for a few hours until ready to serve.
Recipe by TeaTime Magazine at https://teatimemagazine.com/radish-and-goat-cheese-triple-stack-tea-sandwiches/