I prepared only bread and butter with ham.for dinner.
I served only bread and butter with ham for dinner.
It sounds more natural with this word order. 'Bread and butter' is a standard collocation, not bread with butter. I have change it to prepared and served - otherwise you are saying that every single day of your life, you serve/prepare only those things for dinner. The use of
I don´t know if it´s a sandwich, but it´s possible. I mean a typical Czech kinde of bread which we buy at the baker´s and we cut it into slices (at home) and put butter and then ham on it. I think you can often buy such a kind of bread in German.