The Milky Way bar is a chocolate bar distributed by the Mars confectionery company. The American version of the Milky Way bar is made of chocolate-malt

Malt

Malt is germinated cereal grains that have been dried in a process known as "malting". The grains are made to germinate by soaking in water, and are then halted from germinating further by drying with hot air...

 nougat

Nougat

Nougat is a variety of similar traditional confectioneries made with sugar and/or honey, roasted nuts , and sometimes chopped candied fruit. The consistency of nougat can range from soft and chewy to hard and crunchy depending on its composition, and it is used in a variety of candy bars and...

 topped with caramel

Caramel

Caramel is a beige to dark-brown confection made by heating any of a variety of sugars. It is used as a flavoring in puddings and desserts, as a filling in bonbons, and as a topping for ice cream, custard and coffee....

 and covered with milk chocolate and is very similar to the Mars bar

Mars Bar

Mars is a chocolate bar manufactured by Mars, Incorporated. It was first manufactured in Slough, Berkshire in the United Kingdom in 1932 as a sweeter version of the US Milky Way bar which Mars, Inc. produced...

 sold in other countries. The non-US Milky Way bar, on the other hand, is not topped with caramel and is therefore similar to the American 3 Musketeers bar.
The Milky Way bar was created in 1923 by Frank C.