Process flour and butter in a food processor until mixture resembles coarse meal. Add cheese and pepper; pulse 6 to 8 times or until combined. With processor running, gradually add water through food chute, and process just until dough forms a ball.
Drop dough by level tablespoonfuls 2" apart onto ungreased baking sheets. Flatten each cookie with the bottom of a glass; gently press 1 pecan half into center of each cookie, if desired.
Bake in batches at 400º for 12 minutes. Let cool on baking sheets 2 minutes. Remove cookies to wire racks to cool. Store in an airtight container.
Note: To toast pecan halves, coat them with cooking spray, and place in a large skillet. Cook over medium heat 6 to 7 minutes or until lightly toasted. Remove pecans to a paper towel, and sprinkle lightly with salt. Let cool.