mince pie in Britain, is a miniature round pie, filled with mincemeat: typically a mixture of dried fruits, chopped nuts and apples, suet, spices, and lemon juice, vinegar, or brandy. Although the filling is called mincemeat, it rarely contains meat nowadays.
In N. America the pie may be larger, to serve several people. The large size is an innovation, for the original forms were almost always small. The earliest type was a small medieval pastry called a chewette, which contained chopped meat or liver, or fish on fast days, mixed with chopped hard-boiled egg and ginger. This might be baked or fried. It became usual to enrich the filling with dried fruit and other sweet ingredients.