Using a 1½-inch round cutter, cut 32 shapes from frozen bread.
Melt 2 tablespoons butter in a large nonstick sauté pan over medium-high heat. Add bread rounds, and grill on one side until golden brown, working in batches if necessary. Remove bread rounds, and melt remaining 2 tablespoons butter in sauté pan. Return bread rounds to pan to grill other side. Let cool on wire racks.
Place peanut butter in a pastry bag fitted with a large open-star tip (Wilton #1M). Pipe a decorative swirl of peanut butter onto grilled bread rounds. Place a banana slice on top of peanut butter side of 16 bread rounds, and top with remaining grilled bread rounds, peanut butter side down. Secure with a decorative frilled pick, if desired.
Serve immediately.
Recipe by TeaTime Magazine at https://teatimemagazine.com/thats-alright-mama-grilled-peanut-butter-banana-tea-sandwiches-recipe/