PREHEAT oven to 325°F. Grease 2 large baking sheets.
STIR together flour, pumpkin pie spice, baking soda and salt in a large bowl.
MELT butter in the microwave in a medium bowl. Add cream cheese and break up with the back of a wooden spoon. Let stand until butter has cooled and cream cheese is soft. Beats in sugars until well blended then beat in extract and egg. Add to dry ingredients and beat just until mixed. Stir in chocolate chunks and walnuts.
SCOOP dough using a mounded small ice cream scoop onto baking sheets. Sprinkle lightly with sea salt.
BAKE for 15 to 17 minutes or until the cookie center feels set when gently touched. Cool completely on baking sheets. Store in an airtight container.