Step 1
Preheat oven to 350°F and line two 12-cup standard muffin pans with baking cups.
Step 2
Whisk together flour, cocoa, baking powder, baking soda, and salt in a large bowl; make a well in the center of the mixture. Add C&H® Granulated Sugar Easy Baking Tub, C&H® Light Brown Sugar, eggs, egg yolk, milk, yogurt, oil, and vanilla to flour mixture; whisk in just until incorporated. Dissolve instant espresso in boiling water; add to batter and whisk in just until smooth. Fold in chopped chocolate.
Step 3
Use a medium cookie scoop coated with nonstick spray to fill each baking cup 2/3 full of batter.
Step 4
Bake for 17 to 18 minutes, until cupcakes spring back to the touch and a toothpick inserted in the center comes out clean. Let cupcakes cool in pans on wire racks for 2 minutes before removing from pans to cool completely.
Step 5
Cook C&H® Granulated Sugar Easy Baking Tub in a heavy saucepan over medium heat, stirring constantly with a heat-resistant spatula. Continue cooking until sugar forms clumps and melts into a light amber colored liquid, about 4-5 minutes.
Step 6
Once the sugar is completely melted, carefully add butter a few pieces at a time, whisking constantly until incorporated.
Step 7
Slowly drizzle in heavy cream while whisking constantly. (The mixture will bubble up rapidly.) Let mixture boil for 1 minute, then remove from heat and pour into a glass bowl. Stir in vanilla and salt. Let caramel sauce cool before using – sauce thickens as it cools.
Step 8
Beat butter and salt in a large mixer bowl on medium speed until smooth. Beat in vanilla. Mix in 2 1/2 cups of C&H® Powdered Sugar on low speed until incorporated. Mix in salted caramel sauce until incorporated. With mixer on low speed, add remaining 2 cups C&H® Powdered Sugar. Increase speed to medium and beat frosting for 1 minute, until light and airy.
Step 9
Transfer frosting to a large piping bag fitted with an open star tip and frost cupcakes. Chill frosted cupcakes for 20 to 30 minutes in the refrigerator, until frosting is firm.
Step 10
Combine chopped chocolate and oil in a microwave-safe bowl. Heat in 20 second increments, stirring after each, until completely melted and smooth. Let the chocolate shell cool for 15 minutes before dipping.
Step 11
Dip the chilled cupcakes in chocolate shell to coat the frosting. Place on a baking sheet and refrigerate for 20 to 30 minutes to set chocolate before serving.
Store leftover cupcakes in the refrigerator up to 3 days. Let stand at room temperature for 20 minutes before serving.