Preheat oven to 350°.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking soda, and salt.
Beat cream cheese and butter with a mixer at medium speed until fluffy. Add sugars, beating until blended. Add egg and vanilla, beating just until blended. Gradually add flour mixture to butter mixture, stirring just until combined. Fold in oats, blueberries, and walnuts. Drop by tablespoonfuls 2 inches apart onto baking sheets.
Bake at 350° for 10 minutes or until lightly browned. Remove from pans, and cool completely on wire racks.