National Geographic has put together a handy chart/calculator to help determine how much is too much. It lists white chocolate, milk chocolate, dark, semi-sweet, baking and cocoa powder.
Spoiler alert: for the average 16 pound cavalier Kling Charles spaniel, it takes as little as one ounce of dark chocolate to make them sick. Five ounces of dark chocolate can kill them. Cocoa powder is much more concentrated and takes less than an ounce before the dog is in danger of death. Milk chocolate is less dangerous. For example, 70 Milk Chocolate Hershey Kisses could kill a Cavalier; 11 will make one sick.
Remember, even if it says Black and Tan Chocolate, it is not to be given to a Black and Tan Cavalier King Charles Spaniel. 😉 Indulge responsibly.
Footnote: How cute are those cake pops in the top photo?! No, I will not be bringing them to the next Cavalier club meeting. Mine would inevitably look like rock monsters instead.