Preparation

• Prepare the streusel by mixing the brown sugar, finely chopped walnuts, chocolate chips, cocoa powder, and cinnamon in a bowl. Set aside.
• In a large bowl, mix the flour, cornstarch, and baking powder and sift to avoid lumps.
• Cream the room temperature butter with the sugar and salt until the mixture whitens and becomes fluffy. This will take about 6 minutes with an electric mixer at medium speed.
• In another container, beat the whole eggs together with the yogurt, lemon juice, and vanilla extract until you obtain a homogeneous mixture.
• Incorporate the butter and the sifted ingredients alternately in three additions, gently folding with a spatula after each addition.
• Add 1/3 of the butter to the liquid mixture and mix until integrated.
• Add 1/3 of the sifted flour and mix until integrated.
• Add another 1/3 of the butter and mix until completely incorporated.
• Add another 1/3 of the flour and mix until homogenized.
• Add the remaining butter and mix until the mixture is uniform.
• Finally add the last third of the flour and mix until you obtain a smooth, lump-free batter.
• Grease the mold with butter and pour in half of the prepared batter.
• Sprinkle the prepared streusel over the batter in the mold.
• Finish filling the mold with the second half of the batter.
• Using a knife, gently stir the batter with circular motions to distribute the streusel.
• Allow the dough to rest in the mold for 1 hour at room temperature.
• When there are 30 minutes remaining before baking, preheat the oven to 180ºC.
• Bake the cake in the preheated oven at 180ºC for approximately 45 minutes, checking if a skewer comes out clean to ensure it is cooked.
• Let the cake cool in the mold placed on a wire rack to cool evenly.