Cleanse the onion, chop it finely and and smothered in butter, until translucent. Sprinkle the flour and fry until golden, stirring constantly. Then, milk and vegetable broth and also continuously stirred in order not to become no lumps. Sprinkle with salt, pepper and cumin and cover with lid by letting it boil on low heat for about 30 minutes. During this time shredding the feta cheese grater in small pieces and minced meat garlic and onion. 1/3 of the feta cheese is added to the soup while stirring continuously. The rest of the feta cheese mix with the onion and garlic and place in each dish. Once soup is ready can be sprinkled with croutons.