Beat first 3 ingredients at medium speed with an electric mixer 2 to 3 minutes or until light and fluffy. Add flour and cinnamon, beating well. (Dough will be stiff.)
Roll dough to 1/8-inch thickness between sheets of parchment paper. Remove top sheet of parchment, and invert dough onto a lightly greased baking sheet. Remove parchment paper, and press pecans evenly into dough.
Bake cookies at 350° for 15 minutes; reduce heat to 250°, and bake 10 more minutes. Remove from oven, and cut cookies (while dough is hot) into 3- x 1 1/2-inch rectangles, using a pizza cutter. Cool on a wire rack.
Note: Sprinkle cookie crumbs that remain from cutting over bowl of vanilla ice cream.