Split sausages in half lengthwise. Brown slowly in a skillet (turning often and draining off fat as it collects) until brown and cooked through, about 15 minutes.
In another skillet, heat 2 tablespoons butter over low heat.
Add apple slices and saute, turning often, until nicely browned and tender. They should be brown at the same time the sausages are ready.
Toast bread and spread with softened butter.
Drain sausages and arrange on toast. Arrange apple slices over sausages.
