Put 1 pastry sheet on work surface;spread half of mustard evenly over pastry. Mix cheese, oregano and garlic powder; sprinkle half of cheese mixture over mustard. Arrange half of prosciutto slices evenly over cheese mixture.
Lightly press prosciutto into cheese. Roll up pastry, jelly roll fashion, starting and 1 side and ending at middle of pastry sheet.
Roll up other side of pastry, jelly roll fashion, until both rolls meet in the middle. Cover and chill roll at least 30 minutes. Repeat procedure with remaining pastry sheet, mustard, cheese mixture and ham.
Cut rolls crosswise into 1/2 inch thick slices. Slices will resemble a figure “8”. Place slices on lightly greased baking sheets. Brush top of each Palmier with beaten egg.
Bake at 350 for 25 minutes or til puffed and golden. Serve warm or at room temperature. Makes about 3 1/2 dozen.