Wills in Spain are notarised. These can be drawn up quite easily with a Spanish notary in two languages. However, caution is required since the notary might not be familiar with applicable law in your home country. Great difficulties can arise from such contradictions regarding wills.
In Spain, joint wills are not possible. Handwritten wills are however possible, but not very common. Before drawing up a will in Spain a consultation with a lawyer knowledgeable in this area is essential.