Chop carrots and onions in a food processor. Melt butter in large soup kettle, and cook carrots and onion over medium-low heat for 30 minutes or until vegetables are tender, stirring occasionally. Remove from the heat and cool slightly.

In a food processor (or blender) place 1/2 cup of the chicken broth and the cooled vegetables; cover and process until blended.

Return to soup kettle and stir in puree, basil, sugar, salt, pepper and remaining broth. Bring to a boil. Reduce heat; simmer, uncovered for 30 minutes.

Reduce heat to low. Gradually stir in evaporated milk; heat through (do not boil).

Garnish with freshly grated Parmesan cheese.