Prepare the Bread: Begin by laying out eight slices of crustless bread on a clean surface. Spread mayonnaise on one side of each slice.

Layer the Fillings: Stack two slices of cheese on four of the mayonnaise-covered slices, followed by a layer of deli ham. Add mustard if desired.

Assemble the Sandwiches: Place the remaining four slices of bread on top of the filled slices, mayonnaise side down, and press gently.

Cut Out the Christmas Trees: Use a tree-shaped cookie cutter to create your fun festive shapes.

Arrange and Serve: Transfer the sandwiches onto a festive platter and arrange them playfully.