• Start preheating the oven to 320F/160C. Lower heat will allow for the cake to rise more evenly (with minimal doming).

  Grease a large baking dish (30/22cm or 12/8in) and set it aside. Then, sift all of the dry ingredients (other than sugar and salt) into a large mixing bowl.
  200 grams buckwheat flour , 1½ teaspoon baking powder, ½ teaspoon baking soda, 40 grams Dutch-process cocoa powder
• Add sugar and salt to the sifted dry ingredients and stir to incorporate.
  1 teaspoon salt, 225 grams sugar,
• Add all the liquid ingredients (except the hot water) to the dry ingredients and whisk until smooth.
  2 medium-large eggs,, 190 grams milk,, 90 grams sunflower or other oil
• Next, add the boiling hot water and whisk again. Don't worry - it won't curdle the eggs!
  190 gram hot water or coffee
• Finally, pour the batter into the greased baking dish and bake for 40 min on the middle oven rack.

  Once the cake is done, let it cool completely before preparing the frosting!

  Note: if your cake domes, bake it at a lower temperature next time and/or use cake strips.

Frosting

• To make frosting you will need to sift the cocoa powder and the confectioners' sugar, then add cold mascarpone cheese.

  Mix mascarpone with the dry ingredients using an electric mixer until evenly incorporated (1-2 minutes).
  ⅓ cup Dutch-process cocoa powder, ⅔ cup powdered sugar, 250 grams mascarpone cheese,
• Then, add the cold heavy cream and keep mixing until it reaches the desired consistency. Be careful not to overmix or the cream will curdle!
  1 cup heavy cream,
• Frost the cake right away and top with your favorite toppings (like crushed buckwheat oatmeal cookies)!