Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans, then line the bottoms with parchment paper. This helps prevent sticking and ensures easy release.

In a large bowl, whisk together the flour, granulated sugar, baking powder, and salt. Set aside.

In a separate medium bowl, using an electric mixer, beat the softened butter until creamy. Add the eggs one at a time, beating well after each addition. Stir in the milk, vanilla extract, lemon zest, and fresh lemon juice until just combined.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined and no streaks of flour remain. Be careful not to overmix, as this can lead to a tough cake.

Divide the batter evenly between the two prepared cake pans. Bake for 28-32 minutes, or until a wooden skewer inserted into the center comes out clean. The cakes should be lightly golden.

Let the cakes cool in the pans on a wire rack for 10-15 minutes before inverting them onto the wire rack to cool completely. Allow to cool fully before frosting, at least 1-2 hours.

In a medium saucepan, combine the raspberries and granulated sugar. Cook over medium heat, stirring occasionally, until the raspberries break down and release their juices, about 5-7 minutes.

In a small bowl, whisk together the cornstarch and water until smooth to create a slurry. Pour the cornstarch slurry into the raspberry mixture, stirring constantly. Bring to a gentle boil and cook for 1-2 minutes, until thickened. Remove from heat.

Stir in the fresh lemon juice. Transfer the filling to a bowl and cover directly with plastic wrap to prevent a skin from forming. Let cool completely in the refrigerator for at least 30 minutes, or until firm.

In a large mixing bowl, using an electric mixer, beat the softened cream cheese and butter together on medium speed until smooth and creamy, about 2-3 minutes. Make sure there are no lumps.

Gradually add the sifted powdered sugar, 1 cup at a time, mixing on low speed until combined, then increase speed to medium and beat until fluffy. Add the lemon zest, 2 tablespoons of lemon juice, vanilla extract, and salt. Beat until well incorporated.

Taste the frosting and add the remaining tablespoon of lemon juice if you desire a tangier flavor. Beat for another minute until light and airy.

Once the cake layers are completely cool, use a serrated knife to level the tops of the cakes if necessary, creating flat surfaces.

Place one cake layer on your serving plate or cake stand. Spread about half of the raspberry filling evenly over the top, leaving a small border (about 1/2 inch) around the edge.

Carefully place the second cake layer on top. Spread the remaining raspberry filling over this layer, again leaving a border.

Frost the entire cake (top and sides) with the lemon cream cheese frosting using an offset spatula or butter knife. Start with a thin crumb coat, chill for 15 minutes, then apply the final layer of frosting.

Garnish with fresh raspberries and lemon slices or zest, if desired. Serve immediately or refrigerate until ready to serve.