In a small bowl, combine flour, cocoa, and baking soda. Mix well. In a large bowl, beat the sugars and butter until light and fluffy. Add vanilla and eggs; beat well. Add flour mixture; blend well. Stir in 1/2 cup of pecans. For each cookie, with floured hands, shape about 1 tablespoon for dough around a Rolo, covering completely. In a small bowl, combine rest of pecans and 1 tablespoon sugar. Press one side of each ball in pecan/sugar mixture. Place nut side up on ungreased cookie sheet. Bake 7-10 minutes or until set and slightly cracked.