Cafe Bombon was made popular in Valencia, Spain, and spread gradually to the rest of the country. I've had it and loved it on holidays but recently my Spanish friend Yesica reintroduced it to me in her lovely kitchen.
A café bombón uses espresso served with sweetened condensed milk in a 1:1 ratio (The Asian version uses ground coffee and sweetened condensed milk at the same ratio). For café bombón, the condensed milk is added to the espresso. For visual effect, a glass is used, and the condensed milk is added slowly to sink underneath the coffee and create two separate bands of contrasting colour - though these layers are customarily stirred together before consumption.
My 8oz Neon Kactus Glass Cup is perfect, I don't like it too sweet so I only add half the condensed milk Yesica adds to hers, stir it through slowly and sit back and enjoy, simple pleasures ☕❤️