
Beat cream cheese, horseradish and mustard in small bowl until smooth.
Spread about 3 tablespoons cream cheese mixture evenly on each tortilla.
Arrange 5 or 6 spinach leaves over cream cheese.
Place 2 slices roast beef over spinach; sprinkle with about 3 tablespoons cheese.
Roll each tortilla up tightly; wrap with plastic food wrap.
Refrigerate at least 4 hours or overnight.
To serve, cut each tortilla into 1-inch slices.