product recommendation of a single product based on customer similarity?

I have been wondering how you can build a model to recommend only one single product to a bunch of customers. So basically the question that I would like to answer with this model is to have a ranking of which customer is most likely to buy one specific product based on the customers similarity to other customers who have this product. I only have positive customers (so only customers who do have the product) but no data on customers who don’t have it. Just to make it clear there exists just one product, I don’t have any data on other products. What algorithm could I use?