Let’s bake this delightful Raspberry Lemon Cake! First, prepare your oven and pans. Preheat oven to 350°F (175°C). Butter and flour two 8-inch round cake pans thoroughly. Lining the bottoms with parchment paper circles is also recommended for extra insurance against sticking. Set pans aside. Ensure butter, eggs, and yogurt are at room temperature.

Separate the 3 large eggs carefully, placing the yolks in one small bowl and the whites in a separate, clean, completely grease-free medium or large mixing bowl (reserve whites for later).

In a large bowl (or the bowl of your stand mixer fitted with the paddle attachment), cream the room temperature butter, granulated sugar, and fresh lemon zest together on medium-high speed for 3-5 minutes, until the mixture is very light, pale, and fluffy. Scrape down the sides and bottom of the bowl as needed. Beat in the 3 egg yolks, one at a time, mixing well after each addition. Beat in the teaspoon of vanilla extract.

In a separate medium bowl, whisk together the all-purpose flour, baking powder, salt, and baking soda until well combined.

Now, prepare the meringue component. Using clean, grease-free beaters (from your electric mixer, handheld or stand mixer whisk attachment), beat the reserved 3 egg whites on medium-high speed until they form soft peaks. Soft peaks mean that when you lift the beaters, the peak holds its shape briefly but the tip gently curls over on itself. Do not beat to stiff peaks for this recipe. Set the softly beaten whites aside for a moment.

Add the dry ingredients to the butter/yolk mixture alternately with the room temperature Greek yogurt. Start by adding about one-third of the dry ingredients to the butter mixture, mixing on low speed until just barely combined. Add about half of the Greek yogurt and mix on low until just combined. Repeat with another third of dry ingredients, the remaining half of yogurt, and finish with the last third of dry ingredients. Mix only until just combined after the last addition. Scrape down the bowl.

Now for the crucial folding steps: Gently add about one-third of the softly beaten egg whites to the main batter. Use a large rubber or silicone spatula to fold them in gently, lightening the batter. Add the remaining egg whites and continue to fold gently but thoroughly, scraping from the bottom up and over, rotating the bowl, until no white streaks remain. Be careful not to stir vigorously or deflate the air you incorporated.

Finally, gently fold in the fresh or frozen (do not thaw!) raspberries using your spatula. Use just a few folds to distribute them evenly without crushing them or overmixing the batter.

Divide the finished batter evenly between the two prepared 8-inch cake pans. Use an offset spatula to gently smooth the tops. Place the pans on the same oven shelf (if possible) for even baking. Bake for about 30 minutes, or until the centers spring back when lightly touched and the edges are just starting to turn golden brown. A wooden toothpick inserted into the center (avoiding a raspberry) should come out clean or with a few moist crumbs. Do not overbake.

Let the cakes cool in their pans on wire racks for 10 minutes. Then, carefully run a thin knife around the edges to loosen and invert the cakes onto the cooling racks. Peel off the parchment paper and let them cool completely before frosting.

While the cakes cool, make the Lemon Buttercream Frosting. Ensure your butter is properly softened to room temperature. In a large bowl (using an electric mixer), beat the softened butter on medium-high speed until very pale and fluffy, about 3-5 minutes. Gradually add the sifted confectioner’s sugar, about one cup at a time, mixing on low speed until incorporated after each addition.

Once all the sugar is added, beat in the fresh lemon juice, starting with the 4 tablespoons. Add the optional drop of yellow food coloring now if using. Beat on medium-high speed until the frosting is smooth, creamy, and fluffy (another 2-3 minutes). Check the consistency and taste. If it’s too stiff, beat in more lemon juice, 1 teaspoon at a time. If too thin (unlikely), beat in more sifted confectioner’s sugar. If not lemony enough, add a tiny bit more juice (carefully, affects consistency) or 1/4 tsp lemon extract.

Assemble the completely cooled cake. Level the tops of the cakes with a serrated knife if desired. Place one cake layer onto your serving plate or cake stand. Spread a generous amount of the lemon buttercream evenly over the top (about 1 to 1.5 cups). Carefully place the second cake layer on top (upside down for a flat top is good practice). Use the remaining frosting to cover the top and sides of the cake, smoothing it with your offset spatula or creating decorative swirls. Garnish with fresh raspberries or lemon slices if desired. Chill briefly before serving.