Hot chocolate is actually made from melted chocolate, which includes cocoa butter. Because of its higher fat content, true hot chocolate is richer than the original hot cocoa recipe made from cocoa powder.
During the Regency, people drank hot chocolate too, but they drank it unsweetened the way people drink coffee black, and they often drank it in the morning as a way to begin the day rather than as a special treat. In books, I often have a maid bring the characters a breakfast tray with chocolate (they didn't add the word 'hot' as it was implied since that's the only way people drank it) and a pastry. After the heroine goes through the procedures of dressing and having her hair styled, she goes downstairs to the breakfast room and eats her breakfast buffet style, as was the custom in much of England during the Regency.
Since I like my hot chocolate and/or hot cocoa sweet and decadent, most of my heroines do too, but I have people comment on what a strange quirk that is.
Here is my favorite hot cocoa recipe. As you can see, even though it uses cocoa powder and not melted chocolate, it is not low fat :)
My oldest daughter found this recipe years ago here and we've been using it ever since when we want a special treat that tastes far better than instant mix.
Makes 4 servings
3/4 cup white sugar
1 pinch salt
1/3 cup boiling water
3 1/2 cups milk
3/4 teaspoon vanilla extract
1/2 cup half-and-half cream
Combine the cocoa, sugar and pinch of salt in a saucepan. Blend in the boiling water. Bring this mixture to an easy boil while you stir. Simmer and stir for about 2 minutes. Watch that it doesn't scorch.
Stir in 3 1/2 cups of milk and heat, stirring constantly, until very hot, but do not boil!
Remove from heat and add vanilla.
Image downloaded from Wikimedia commons