Ingredients :

• Plain yogurt — This is the boss here. Use a full-fat yogurt if you can — not low-fat, not 0%. The fat is what provides the moisture. A classic stirred yogurt works very well. You can also use Greek yogurt; the batter will be a bit denser but just as good.
• Chocolate chips — Between 100 and 150g depending on your craving level that day. Avoid low-quality chips that melt into a gray puddle — get dark chocolate with at least 50-55% cocoa. Failing chips, a bar coarsely chopped with a knife gives irregular chunks, which is even better.
• Oil — Sunflower or canola, something neutral in taste. No olive oil; it stands out during baking and clashes with the chocolate. Half a pot might seem like little, but it’s enough — the yogurt compensates.
• Baking powder — A whole sachet, not a random teaspoon. This is what gives the muffins their characteristic dome. Check the expiration date if the packet has been sitting around for a while — flat leavening means flat muffins.