Expecting chocolate chips to melt
Cake, cookie, and brownie mixtures that have chopped chocolate bars in them will spill when baked. Chocolate chips, on the other hand, do not fit this description. Anyone who has ever glanced at a platter of chocolate chip cookies will know that, despite being comprised of chocolate, chocolate chips don't melt. Therefore, if you're adding chocolate chips to your batters and doughs with the expectation that they will melt into tiny pools when baked, you might want to think twice because the chips are made to do the exact opposite.
Chocolate chips are more heat-resistant than baking chocolate because they contain less cocoa butter. They hardly ever melt during baking since some even have additional emulsifiers and stabilizers that assist the chips to maintain their structure under heat. The website proposes sprinkling chopped chocolate bars instead, which will result in little pools of melted chocolate in the cookie unless you want bite-sized chunks of solid chocolate in your cookies. If you have no other chocolate on hand and you absolutely must use chocolate chips for melting, melt the chips in the microwave or over a double boiler.
