1. Preheat your oven to 350°F and line a cupcake pan with paper liners to prepare for baking.
2. In a large bowl, whisk together the dry ingredients: 1 ¾ cup flour, ¾ cup unsweetened cocoa powder, 1 ½ cup granulated sugar, 1 ¼ teaspoon baking powder, 1 teaspoon baking soda, and ½ teaspoon salt to ensure even mixture.
3. In a separate bowl, beat 2 large eggs and mix in ¾ cup milk, ⅓ cup vegetable oil, and 1 ½ teaspoons vanilla extract. Slowly add in ¼ cup hot water, mixing carefully to avoid cooking the eggs.
4. Combine the wet ingredients with the dry ingredients gradually, stirring gently to avoid lumps. If desired, fold in ½ cup sour cream or kefir for extra moistness and richness.
5. Spoon the batter evenly into the cupcake liners, filling each about ⅔ full. Bake for 16-18 minutes, checking doneness by inserting a toothpick into the center of a cupcake (it should come out clean).
6. Remove the cupcakes from the oven and let them cool in the pan for a few minutes, then transfer them to a wire rack to cool completely before frosting.
7. While the cupcakes cool, prepare the marshmallow frosting by beating ½ cup unsalted butter in a mixing bowl until creamy. Gradually add 7 ounces marshmallow creme or fluff while continuing to beat.
8. Add 1 teaspoon vanilla extract and sift 2 ½ cups confectioners’ sugar into the mixture a little at a time, beating until smooth and fluffy. Adjust the consistency by adding 1-3 teaspoons milk or heavy cream if necessary.
9. Once the cupcakes are fully cooled, transfer the frosting to a piping bag and frost each cupcake with the marshmallow buttercream.
10. Garnish with mini marshmallows and a light dusting of cocoa powder for an authentic, hot cocoa-inspired touch before serving.