Preheat oven to 350°.
Remove white papery skin from garlic head (do not peel or separate the cloves). Wrap garlic head in foil. Bake at 350° for 1 hour; cool 10 minutes. Separate cloves, and squeeze to extract the garlic pulp. Discard the skins.
Coat a 1-quart soufflé dish with cooking spray; sprinkle bottom of dish with breadcrumbs.
Lightly spoon the flour into a dry measuring cup, and level with a knife. Spoon the flour and salt into a large saucepan, and gradually add milk, stirring with a whisk. Cook milk mixture over medium heat until thick (about 6 minutes), stirring constantly. Remove from heat. Stir in the garlic pulp, cheese, rosemary, and egg yolks.
Beat egg whites and cream of tartar at high speed of a mixer until soft peaks form. Gently fold one-fourth of the egg white mixture into garlic mixture; gently fold in the remaining egg white mixture. Spoon into prepared soufflé dish. Bake at 350° for 50 minutes or until puffy and set.