Melt the butter in boiling water. Add the flour all at once. Stir over medium heat until it forms into a solid mass, as it will do almost at once. Cool for 3 to 4 minutes. ( this is an important step, you do not want to add eggs to hot dough) At this time you can transfer the dough to a mixer and stir in eggs one at a time. Beat until the mixture is smooth, glossy, and stiff.