Chocolate Peanut Butter Cupcakes

Ingredients

• 2 cups sugar
• 1-3/4 cups all-purpose flour
• 3/4 cup baking cocoa
• 1/2 teaspoon salt
• 1/2 teaspoon baking soda
• 1/2 teaspoon baking powder
• 1 cup buttermilk
• 1 cup strong brewed coffee, room temperature
• 1/2 cup canola oil
• 2 large eggs, room temperature
• 1 teaspoon vanilla extract
• FILLING:
• 1/2 cup creamy peanut butter
• 3 tablespoons unsalted butter, softened
• 1 cup confectioners' sugar
• 2 to 4 tablespoons 2% milk
• GANACHE:
• 2 cups semisweet chocolate chips
• 1/2 cup heavy whipping cream
• PEANUT BUTTER FROSTING:
• 1 cup packed brown sugar
• 4 large egg whites
• 1/4 teaspoon salt
• 1/4 teaspoon cream of tartar
• 2 cups unsalted butter, softened
• 1/3 cup creamy peanut butter
• Chocolate curls, optional