Preparation:

Step 1: Preheat the oven and prepare the pans
Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans, or line them with parchment paper to prevent sticking. Set the pans aside.

Step 2: Mix the dry ingredients
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. This ensures that the dry ingredients are evenly distributed and will help with the rise and texture of the cake.

Step 3: Cream the butter and sugar
In a separate large bowl, cream together the softened butter and sugar using an electric mixer. Beat on medium speed until the mixture is light and fluffy, about 3-5 minutes. This step is crucial for creating a light and airy texture in the cake.

Step 4: Add the eggs and flavorings
Add the eggs, one at a time, beating well after each addition. Once the eggs are incorporated, add the lemon zest, fresh lemon juice, and vanilla extract. Continue mixing until the batter is smooth and well combined.

Step 5: Combine the wet and dry ingredients
Alternate adding the dry ingredient mixture and the buttermilk to the wet ingredients, beginning and ending with the dry ingredients. Mix until just combined after each addition. Be careful not to overmix, as this can make the cake dense.

Step 6: Bake the cake
Divide the batter evenly between the prepared cake pans. Smooth the tops with a spatula. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center of the cakes comes out clean. Once baked, allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

Step 7: Make the raspberry frosting
While the cakes are cooling, prepare the frosting. In a small saucepan, heat the raspberries over medium heat, mashing them with a spoon or potato masher until they release their juices. Simmer for about 5 minutes, then strain the mixture through a fine mesh sieve to remove the seeds. Let the raspberry puree cool.

In a separate large bowl, beat the softened butter until smooth. Gradually add the powdered sugar, ½ cup at a time, and continue to beat until light and fluffy. Add the cooled raspberry puree, lemon juice, and vanilla extract to the frosting. If the frosting is too thick, add a tablespoon of heavy cream to reach the desired consistency.

Step 8: Frost the cake
Once the cakes have completely cooled, place one layer of cake on a serving plate or cake stand. Spread a generous layer of raspberry frosting over the top of the cake. Place the second layer of cake on top and frost the entire cake with the remaining raspberry frosting. Garnish with fresh raspberries and lemon zest, if desired.