In a large bowl, whisk together the flour, cocoa powder, baking powder, and salt. In another large bowl, whisk together the sugar, heavy cream, oil, eggs and vanilla, until smooth. Pour the wet ingredients into the bowl with the dry ingredients and mix to combine. Whisk in the water until smooth.
Preheat your air fryer to 325 degrees F, air fryer setting. Fill the silicone cupcakes liners or cupcake pan of your choice with batter 2/3 the way full. Air Fry for 9 to 10 minutes or until a toothpick inserted into the center comes out clean. You will have to air fry in batches. Let cool completely on a wire rack.
While the cupcakes are cooling, make the filling by adding the butter to a medium-sized bowl and beat with a hand mixer until smooth. Mix in the marshmallow cream and mix to combine. Add in the powdered sugar and mix until smooth. Fold in the marshmallow cream and mix to combine. Add in the powdered sugar and mix until smooth. Fold in 3 tablespoons of the heavy cream and mix on low until combined, then turn up the speed to medium and beat until smooth and fluffy, about 2 minutes. If it seems too thick to pipe, mix in the additional heavy cream.
Add the filling to a piping bag fitted with a piping tip that can piece the cupcake. Place the piping tip into the center of the cupcake and gently fill the inside. You will feel the cupcake puff up slightly in your hand. Continue with the remaining cupcakes
For the glaze, add the chopped chocolate to a medium-sized bowl. Heat the cream just until it simmers, immediately take it off the heat, and pour over the chocolate. Let sit for about 4 to 5 minutes. Whisk to combine until smooth.
Dip the tops of the cupcakes into the glaze, or you can smooth a little on top with a butter knife or spatula.
Take any leftover filling and pie a curly q on top of each cupcake.
Plate, serve, and enjoy!