From Mrs. Beeton's Book of Household Management, which is in the public domain:
TO MAKE HOT BUTTERED TOAST.
1726. A loaf of household bread about two days old answers for making toast better than cottage bread, the latter not being a good shape, and too crusty for the purpose.
Cut as many nice even slices as may be required, rather more than 1/4 inch in thickness, and toast them before a very bright fire, without allowing the bread to blacken, which spoils the appearance and flavour of all toast.
When of a nice colour on both sides, put it on a hot plate; divide some good butter into small pieces, place them on the toast, set this before the fire, and when the butter is just beginning to melt, spread it lightly over the toast. Trim off the crust and ragged edges, divide each round into 4 pieces, and send the toast quickly to table. Some persons cut the slices of toast across from corner to corner, so making the pieces of a three-cornered shape.
Soyer recommends that each slice should be cut into pieces as soon as it is buttered, and when all are ready, that they should be piled lightly on the dish they are intended to be served on. He says that by cutting through 4 or 5 slices at a time, all the butter is squeezed out of the upper ones, while the bottom one is swimming in fat liquid. It is highly essential to use good butter for making this dish.
The slow flame toasting of bread results in a very different texture than you will get from an electric toaster; less dry, less crumby. The outside is crisp, but the center becomes more springy and chewy because of the slow contraction of the glutens in the bread as it gradually turns golden and finally then a caramel brown. If you have no fireplace, you can just use the oven broiler. At an open flame, you can either make a campfire toaster out of wire (a wire hanger works well, and is the Boy Scouts method - bend the arms down and then fold up to make a bread-holding device which can be attached to a stick for easy bread-toasting).
Use excellent butter. The butter is practically the whole point. Get spendy on the butter. Get local, or Lurpak.