Step 1: Preheat the Oven
Preheat your oven to 350°F (175°C).
Grease and flour two 9-inch round baking dishes.
Step 2: Prepare Dry Ingredients
In a medium bowl, whisk together 2 cups of all-purpose flour, 1 ½ teaspoons of baking powder, ½ teaspoon of baking soda, and ½ teaspoon of salt. Set aside.
Step 3: Cream Butter and Sugar
In a large bowl, cream together 1 cup of softened unsalted butter and 1 ½ cups of granulated sugar until the mixture is light and fluffy.
Step 4: Add Eggs and Vanilla
Add the eggs to the butter and sugar mixture three times, mixing well after each addition.
Stir in 1 teaspoon of vanilla extract.
Step 5: Combine Wet and Dry Ingredients
Slowly combine the dry ingredients with the wet ingredients, alternating with 1 cup of buttermilk.
Start with the dry ingredients and finish with them, mixing only until everything is combined.
Step 6: Divide Batter and Bake
Evenly distribute the batter between the prepared cake pans.
Smooth the tops with a spatula.
Place the pans in the preheated oven and bake for 30 minutes or until a toothpick inserted into the center comes out clean.
Step 7: Prepare Filling
While the cakes are baking, prepare the filling by whipping 1 cup of marshmallow cream, ½ cup of powdered sugar, and 1 teaspoon of vanilla extract until stiff peaks form.
Step 8: Assemble the Cake
Once the cakes are cooled, spread the prepared filling over the top of one cake layer.
Place the second cake layer on top.
Step 9: Make Chocolate Glaze
For the chocolate glaze, melt 1 cup of semi-sweet chocolate chips, ½ cup of heavy cream, and 2 tablespoons of unsalted butter in a heatproof bowl over simmering water.
Stir until smooth.
Step 10: Glaze the Cake
Pour the chocolate glaze over the assembled cake, letting it drip off.
Step 11: Allow to Cool
Allow the cake to cool completely before serving for optimal texture and flavor.