Can I use chocolate chips instead of chunks?
Yes. Use the same amount. You will get a slightly more uniform look and fewer melty pools, but the muffins will still be great. If you have chips, I like doing half chips and half chopped chocolate for the best of both worlds.
Why did my muffins turn out dense?
The usual culprits are overmixing or too much flour. Stir just until you do not see dry streaks, and if possible, spoon and level your flour instead of scooping straight from the bag.
How do I get taller muffin tops?
Three things: start with a hot oven, fill the cups about 3/4 full to nearly full, and let the batter rest 10 minutes before baking. The rest step can help hydrate the flour for a more tender crumb and can also help the muffins dome up nicely. Also, make sure your baking powder is fresh.
Can I make these mini muffins?
Yes. Bake at 425°F for 2 to 3 minutes, then reduce to 350°F and bake 6 to 10 minutes more, until the tops spring back when lightly pressed and a toothpick comes out with a few moist crumbs. For extra confidence, aim for an internal temperature of about 200 to 205°F.
Can I add berries or nuts?
Absolutely. Add up to 3/4 cup chopped toasted walnuts or pecans, or 1 cup blueberries. If using blueberries, toss them with 1 teaspoon flour first to help prevent sinking. Keep the mix-ins about the same total volume so the batter is not overloaded. If you add nuts in addition to all the chocolate, the bake time may run 1 to 2 minutes longer.
What does espresso powder do?
It does not make the muffins taste like coffee. It just deepens the chocolate flavor. You can skip it if you do not have it.