This recipe comes from my rich pound cakes Lenôtre culinary school course collection. In my Pastry Fundamentals course, you will find the other greatest classics. For this recipe, I used a nonstick mini loaf pan and a medium size fluted brioche mold (6-inch/15cm diameter). Avoid large baking molds or it'll end up drier. Grease pans with soften butter and cooking spray or butter and flour. Molds can also be lined with wax paper. Double the recipe is using a large bundt cake mold.
Sift flour and baking powder; set aside. Microwave butter for a few sec to soften. In a stand mixer fitted with the paddle attachment, beat butter with salt and powdered sugar until creamy consistency. Add one egg at the time and vanilla but save the last egg. If the batter does break during mixing still, warm up mixing bowl using your kitchen blowtorch. Once batter is smooth, set mixer speed on low speed and incorporate the sifted powders. Add the remaining egg and continue mixing until homogenized. Meanwhile, mix together warm milk and cocoa powder with a small whisk. Mix chocolate mixture with 225g of the vanilla batter. Reserve both mixtures.
Begin with a layer of vanilla batter and superimpose with chocolate batter. Repeat twice. To create the swirl, run a wooden skewer through the batter in a figure-eight motion. Bake right away, or refrigerate cake for up to 3 days.
Preheat oven to 350ºF/180ºC. Bake for 45 minutes or until a knife inserted in the center comes out clean. Let sit for about 10 min and unmold. Baked cake can be wrapped in plastic film and kept refrigerated for up to 5 days. Enjoy!