Leeks au Gratin

• 12 leeks
• 4 tablespoons butter
• 4 tablespoons flour

Wash leeks; cut off roots and green tops to within an inch of white. Split leeks from top almost to root end and wash thoroughly under running water. Simmer in boiling salted water for 20 minutes, or until tender. Drain thoroughly.

Melt butter in top of double saucepan; blend in flour and cook over water, stirring constantly, until smooth. Add hot milk gradually and cook, stirring const