Unroll the pie dough and cut out 12 (3 inch) circles using a round cookie cutter or small bowl. Reroll the pie dough to get all 12 circles if needed. Line the cavities of the muffin tin with the pie dough and evenly distribute the chocolate chips and walnuts between them. Set aside
Combine the brown sugar and butter in a medium bowl and beat with a mixer until combined. Add the corn syrup, eggs, flour and vanilla and beat until fluffy, about 3 minutes. Divide the butter filling between the prepared pie crusts, about 2 tbsp each.
Bake for 15 minutes, or until filling is a deep golden brown and crust is golden brown. Let cool at least 10 minutes before removing from pan. Dust with powdered sugar before serving. Enjoy!