Cream fat and sugar with the whisk of the hand mixer. Stir in eggs and milk bit by bit. Mix flour and baking powder and stir into the fat-egg mixture. Divide the dough into three. Chop 50 g chocolate coating, melt over a warm water bath and stir into one third of the dough with vanilla pulp.
Stir nuts under the 2nd third, 1 teaspoon of Matcha under the last third.
Grease a box mould (30 cm long; 2 litres capacity) and sprinkle with breadcrumbs. Fill in doughs alternately. Use a fork to marble the dough in streaks.
Bake in a preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: see manufacturer) for approx. 1 1/4 hours (stick test). Cover with foil after about half of the baking time. Remove the cake from the oven and let it cool down on a cake rack for about 30 minutes.
Remove the cake from the mould and let it cool down completely.
Chop the rest of the chocolate coating. 3/4 and melt over a hot water bath. Melt the rest of the couverture over a second hot water bath and stir in 1 teaspoon of Matcha. Remove melted chocolate from the waterbaths and let it cool down a bit.
First run white, then Matcha couverture streaky on the cake. Let the couverture cool down, arrange the cake on a plate.