1. Cream butter, peanut butter, 1 c sugar and brown sugar.
2. Add eggs one at a time, beating well after each addition.
3. Combine flour, soda and salt, gradually add to creamed mixture.
4. Roll into 1 1/2 to 2 inch balls then roll in remaining 1/2 c sugar.
5. Place 2 apart on ungreased baking sheets.
6. Using end of wooden spoon handle make an indentation in center of each cookie.
7. In small mixing bowl beat Peanut Butter and cream cheese until smooth.
8. Add sugar, egg yolk and vanilla and mix well.
9. Spoon about 3/4t of filling into the center of each indentation.
10. Bake at 350 for 12-15 minutes.
11. Allow cookies to rest 1-2 minutes then transfer to wire rack and let cool.
12. Melt chips in microwave and stir until smooth.
13. Dip bottom of each cookie into chocolate, shake off excess then lay bottom up on waxed paper.
14. Refrigerate until set.
15. For topping, in a small sauce pan melt butter, whisk in powdered sugar and cocoa.
16. Gradually add water, whisk until smooth.
17. Stir in vanilla.
18. Drizzle over cookies, chill until set.
19. Store in air tight container, keep in refrigerator.