Have bakery cut bread into lengthwise slices 1/4 inch thick.
Trim crusts; flatten each slice to 1/4-inch thickness with rolling pin.
Spread each slice bread on one side with butter.
Combine deviled ham and relish; spread about 1/4 cup ham mixture on each buttered slice.
Roll up bread, jelly-roll fashion, beginning at narrow end.
Wrap, label, and freeze.
If desired, spread rolls with mayonnaise; roll in parsley to coat.
Cut into 3/8inch slices to form pinwheels.