2 cups 60% Cacao Bittersweet Chocolate Chips
8 tablespoons (1 stick) unsalted butter, cut into pieces
1/2 cup plus 2 tablespoons all purpose flour
1/4 teaspoon baking powder
3 large eggs
3/4 cup sugar
1/4 teaspoon salt
1 cup coarsely chopped walnuts
1 cup mini marshmallows
- Preheat the oven to 350 degrees with a rack in the lower third.
- Grease or spray the top surface of the pan with nonstick spray and line the cups with paper liners.
- In the top of a double boiler or in a heatproof bowl over barely simmering water, melt 1 1/4 cups of the chocolate chips with the butter, stirring frequently until melted and smooth.
- Remove the chocolate from the heat and let it cool to lukewarm. Meanwhile, in a small bowl, whisk the flour and baking powder together thoroughly.
- In a large bowl, beat the eggs, sugar, and salt with an electric mixer on high speed for 2 to 3 minutes until the mixture is very pale and thick.
- Scrape the warm chocolate over the egg mixture and fold it in with a large rubber spatula.
- Sprinkle the flour into the bowl with half of the remaining chocolate chips and half of the walnuts. Fold just until the ingredients are blended.
- Divide the batter evenly among the lined cups. Sprinkle the tops with marshmallows followed by the remaining walnuts and the remaining chocolate chips.
- Bake 18 to 20 minutes until the marshmallows are golden brown.
- Set the pan on a rack to cool for 5 minutes.
- Run the tip of a table knife around the top of each cupcake to detach any melted marshmallow or chocolate from the pan. Let the cupcakes cool until firm enough to remove from the pan.
- Serve warm or at room temperature.