Preheat oven to 350 degrees. Lightly grease 2 baking sheets with cooking spray.
In a medium bowl, stir together first 7 ingredients.
Using an electric mixer, beat butter and sugar at medium speed until fluffy.
Add eggs and vanilla, scraping down sides of bowl to mix evenly.
With mixer on low, gradually add flour mixture. Beat just until blended.
Stir in oats and chopped pecans and raisins if using.
Drop dough by 1/4 cupfuls onto prepared baking sheets and flatten flightly with your hand.
Bake 12 to 14 minutes. Cookies should NOT have browned around the edges and middle should look under-done. Cool for 2-3 minutes on baking sheets and remove to wire racks to cool completely. (You will have to cook in 2 batches to get all the cookie dough baked.)
For glaze, combine all ingredients in a mixing bowl and beat with an electric mixer until smooth.
Drizzle cooled cookies with glaze.