Preheat your oven to 175°C (350°F) and grease your cake pans thoroughly, lining the bottoms with parchment paper

In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt until evenly combined

In another bowl, mix milk, oil, eggs, and vanilla extract until smooth

Gradually add the wet mixture into the dry ingredients while stirring continuously

Mix until a smooth batter forms with no lumps

Slowly pour in the boiling water and stir carefully until fully incorporated; the batter will be thin, which is normal

Divide the batter evenly between the prepared pans

Tap pans lightly on the counter to remove air bubbles

Place in the oven and bake for 30–35 minutes or until a toothpick inserted into the center comes out clean

Remove cakes from the oven and allow them to cool in the pans for about 10 minutes

Carefully transfer the cakes onto a cooling rack and let them cool completely

While cakes cool, prepare the frosting by beating softened butter until creamy

Add cocoa powder and mix until fully blended

Gradually add powdered sugar, mixing on low speed to avoid spills

Add vanilla extract and a pinch of salt

Pour in milk a tablespoon at a time until the frosting reaches a smooth, spreadable consistency

Place one cake layer on a serving plate and spread a generous amount of frosting evenly on top

Add the second cake layer and frost the top and sides evenly

Smooth the frosting with a spatula or create decorative swirls as desired

Let the cake sit for at least 30 minutes before slicing to allow flavors to settle