Place each of the ham halves on top of the cheese and tomato halves, and get ready to press them. If you have a panini press, leave them for around 3-5 minutes, and serve them sizzling hot.However, if you don’t have a press at home, you need not worry. Instead, get yourself a large pan, get it nice and hot over high heat, and carefully place your paninis into the pan. From there, use a large kitchen utensil, such as a cooking pot, to apply pressure to the top of the paninis. You will have to judge the time yourself, but a good rule of thumb is to look at the cheese – once the cheese is melting, your paninis should be nearly good to go.