Pre-heat oven to 350 degrees.
Line 2 baking sheets with parchment paper.
In a medium bowl with an electric mixer on high-speed, cream the butter, brown sugar, egg and vanilla.
Mix in dry ingredients; just until blended.
Fold in oats, turtles, and pecans.
CHILL THE DOUGH for 20 minutes in the refrigerator.
Drop cookies using a large ice cream scoop onto the baking sheets lined with parchment paper.
Bake 15 minutes until the edges are golden but still wet looking in the middle.
Cool on a wire rack.