Preparation Steps:

• Preheat your oven to 350°F (175°C). This ensures that your cupcakes bake evenly and rise beautifully.
• Line your muffin tin with parchment liners to prevent sticking and make cleanup a breeze.
• In a medium bowl, melt the stick of unsalted butter. Allow it to cool slightly before using it in the batter to avoid cooking the eggs.
• In a large mixing bowl, whisk together the all-purpose flour, sifted cocoa powder, baking soda, baking powder, and salt. This step is crucial for even distribution of the leavening agents.
• In another bowl, combine the melted butter, canola oil (or coconut oil), granulated sugar, eggs, egg yolk, and vanilla extract. Beat until smooth and creamy.
• To the wet mixture, add the buttermilk and hot water, mixing until well incorporated.
• Gradually add the dry ingredients to the wet ingredients, mixing gently until just combined. Be careful not to overmix; a few lumps are perfectly fine.
• Gently fold in the semi-sweet chocolate chips, ensuring they are evenly distributed throughout the batter.
• Divide the batter evenly among the prepared muffin tin, filling each liner about two-thirds full.
• Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Allow the cupcakes to cool in the pan for about 5 minutes before transferring them to a wire rack.
• In a large mixing bowl, beat the stick of unsalted butter until creamy. Gradually add the confectioners' sugar and cocoa powder, mixing on low speed until combined. Add the buttermilk, salt, and vanilla. Beat on high speed for 2-3 minutes until light and fluffy.
• Once the cupcakes are completely cool, frost each one generously with the cocoa frosting. You can use a piping bag for a decorative touch or simply spread it on with a spatula.