i use natty peanut butter all the time when cutting i usually use and isocaloric diet (40 pro / 30 carbs / 30 fat ) and i would say about 80% of my fat intake is from natty peanut butter mixed in my oatmeal.....
as far as a meal plan for tryin to lose 10-15lb....if you like peanut butter and some carbs i would try the isocaloric method....calorie wise for a day look to take in: weight X 12. if you are not too concerned with muscle loss than you can go lower if you feel.....i would try to use mostly LoW GI carbs if possible, and if you feel you need to refeed when necessary (bodyweight x 15 for a day 60% carbs) ......a specific meal plan would be hard to make based on i dont know what resources you have to eat or what you like to eat but if you follow the guideline above you should see some results i know i have......
oh yeah hit the cardio too!!!