Start by turning your oven on to 350°F (175°C) so it can preheat. While that’s heating up, grease your baking pan and line it with parchment paper to prevent sticking.

Now, in a large bowl, sift together all your dry ingredients: flour, cocoa powder, baking powder, baking soda, and salt. Set that aside.

In another bowl, combine the sugars, eggs, buttermilk, oil, and vanilla. Whisk everything together until it’s smooth and well blended.

Slowly add the dry ingredients to the wet mixture. Stir gently—don’t overmix. Once combined, pour in the hot water and stir again. The batter will seem very thin, but that’s exactly how it should be.

Pour it into your prepared baking pan. Put it in the oven and bake for around 28 to 32 minutes. It’s done when a toothpick inserted in the center comes out clean. Let the cake cool completely in the pan.

For frosting, take your butter and beat it until it’s creamy and light. Add the cocoa powder and mix that in well.

Next, start adding powdered sugar little by little. While doing that, alternate with small splashes of milk to keep the texture smooth. Keep beating until the mixture becomes fluffy.

Add a bit of vanilla and a pinch of salt. If the icing is too thick, add a bit more milk until you get the consistency you like.

Once the cake is completely cool, use a spatula to spread the icing evenly over the top. Smooth it out as best you can.

Stick the whole cake in the fridge for at least 30 minutes. This helps the texture set nicely kind of like a chilled or frozen cake.