Prepare the oven and pan: Preheat your oven to 350°F (175°C). Lightly grease an 8-inch round cake pan or line it with parchment paper to prevent sticking. Set aside while you prepare the batter.

Mix the wet ingredients: In a large mixing bowl, crack the eggs and whisk them with granulated sugar and brown sugar until the mixture becomes slightly pale and smooth. Add the yogurt, oil (or melted butter), and vanilla extract, then continue whisking until everything is fully combined and creamy in texture.

Combine the dry ingredients: In a separate bowl, mix together the ground walnuts, almond flour, baking powder, cinnamon, and salt. Stir well so the leavening and spices are evenly distributed throughout the mixture.

Make the batter: Gradually add the dry ingredients into the wet mixture, stirring gently with a spatula or whisk. Mix until you get a thick, uniform batter. Be careful not to overmix, but ensure there are no dry pockets of flour remaining.

Transfer and top: Pour the batter into the prepared cake pan and spread it evenly using a spatula. If desired, sprinkle chopped walnuts on top for added texture and a decorative finish. Lightly press them into the surface so they adhere during baking.

Bake the cake: Place the pan in the preheated oven and bake for 40–45 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean. If the top browns too quickly, you can loosely cover it with foil during the last 10 minutes.

Cool and serve: Remove the cake from the oven and allow it to cool in the pan for about 10–15 minutes before transferring it to a wire rack. Let it cool completely before slicing to help it set properly. Slice into wedges and serve as is or with a light dusting of powdered sugar or a drizzle of honey.