In a medium bowl, beat together butter, cheese and cayenne pepper until thoroughly blended.
Add flour, beating until blended.
Shape dough into log about 9 1/2 inch long and 1 1/2 inches in diameter.
Roll log in sesame seeds, coating completely.
Wrap and refrigerate until firm, several hours or overnight.
To bake wafers, preheat oven to 350 degrees.
Cut chilled dough into 1/4 inch slices.
Place 1 inch apart on ungreased baking sheets.
Press a pecan half in centre of each, if using.
Bake 12-14 minutes or until edges and bottoms are golden.
Remove wafers from baking sheets, cool on racks.
