Caution: Do not make these cookies if you are fleishig. Otherwise you will be craving a glass of milk for the next six hours. Trust me, I know!
Place peanut butter and sugar into a medium bowl and mix to combine. Add the egg and vanilla sugar, mixing until well combined. Set aside.
In the bowl of an electric mixer, beat the margarine and sugars until well combined. Add eggs and vanilla and beat well. Add flour, baking soda, and salt, slowly mixing until just combined. Fold in chocolate chips.
Preheat oven to 350°F.
Roll a 1-inch ball of the peanut butter mixture. Working with damp hands, flatten some fudge cookie dough around the peanut butter ball. Place on greased cookie sheet. Repeat until there is no filling left.
Bake for 16-17 minutes, until cooked through. Let cool on baking sheet for 5 minutes before transferring to a cooling rack.