Why This Recipe Works

Our goal was a moist, just-sweet-enough, generously sized bakery-style muffin with plenty of rich chocolate and butter flavor and a characteristically domed top. Using chopped semisweet chocolate instead of chips gave us a combination of chunks and shards of chocolate pieces. This allowed for the chocolate to meld into the muffin better than chips while also keeping some soft, melty chocolate pockets. Bar chocolate also resulted in zero waxiness at room temperature. Mixing the chocolate in with the dry ingredients instead of folding it in at the end prevented the batter from forming too much gluten, maintaining a tender crumb. To create moist and flavorful muffins, we incorporated sour cream and used nutty browned butter and lots of vanilla. Baking the muffins on a higher rack and at 400 degrees initiated a quick rise to give them nicely domed tops.

Before You Begin

Using homemade parchment paper liners gives the muffins their tall, neat shape and ensures that the muffins will release easily. If you don't want to make your own, you can use tulip liners. Standard muffin liners will also work but won't result in the same tall shape. If you don't have a small drinking glass, a 6-ounce can of tomato paste works well to form the parchment liners in step 1.

Instructions

Adjust oven rack to upper-middle position and heat oven to 400 degrees. Cut twelve 6-inch squares of parchment paper. Press each square around bottom of tapered drinking glass with 1¾- to 2-inch base, creasing paper to form cup shape. Place parchment liners in muffin cups, allowing excess parchment to protrude vertically from cups.

Whisk flour, baking powder, and salt together in medium bowl. Stir in chocolate and set aside. Melt butter in 10-inch skillet over medium-high heat. Cook, stirring constantly with rubber spatula, until butter is dark golden brown and has nutty aroma, 2 to 4 minutes. Transfer browned butter to second bowl and let cool slightly, about 10 minutes.

Whisk 1¼ cups sugar and eggs in large bowl until thick and creamy, about 1 minute. Whisk in sour cream, vanilla, and browned butter. Fold in flour mixture with rubber spatula until just moistened; do not overmix. (Batter will be thick and lumpy with spots of dry flour.)

Using greased ⅓-cup dry measuring cup, portion heaping ⅓ cup batter into each parchment-lined muffin cup; evenly distribute any remaining batter among cups (cups will be full). Sprinkle remaining ¼ cup sugar evenly over batter (about 1 teaspoon per muffin).

Bake until muffins are golden brown and toothpick inserted in center comes out with few crumbs attached, 20 to 25 minutes, rotating muffin tin halfway through baking. Let muffins cool in muffin tin on wire rack for 5 minutes. Transfer muffins to rack and let cool for at least 30 minutes. Serve warm or at room temperature.