Set and preheat oven to 375 °F. In a saucepan, mix butter, milk and salt.
Bring to a boil, then remove from heat and add flour all at once, stirring vigorously with a wooden spoon.
Return to moderate heat and stir constantly until dough leaves sides of pan and forms a ball.
Remove from heat and let cool for about 5 minutes. Add eggs, one at a time, beating hard until dough is smooth.
Add blue cheese. Place rounded teaspoonfuls of dough 2 inches apart on ungreased cookie sheet.
Sprinkle with Parmesan cheese. Bake at 375 °F for 5 minutes, then lower temperature to 350 °F and bake another 10 minutes or until edges are golden brown.
Cool on wire rack, then serve immediately. Refrigerate any leftovers in a container and reheat to serve.