Heat the oven to 350°F (175°C). Grease two 8-inch round cake pans and line the bottoms with parchment.

Whisk the flour, baking powder, and salt together in a medium bowl. In a separate bowl, cream the softened butter and granulated sugar for 3–4 minutes, until pale and fluffy.

Beat in the eggs one at a time, mixing after each addition. Add the vanilla, lemon zest, and lemon juice.

Add the dry ingredients in two or three additions, alternating with the milk or buttermilk. Mix only until the batter is combined.

Toss the raspberries gently with 1 tablespoon of flour, then fold them into the batter. Divide the batter between the prepared pans and smooth the tops.

Bake for 28–35 minutes, until the centers spring back lightly and a toothpick comes out clean or with a few moist crumbs. Cool in the pans for 10–15 minutes, then turn the cakes onto a rack and cool completely.

Beat the butter for the frosting until smooth. Gradually add the sifted confectioners’ sugar, then mix in the lemon zest, lemon juice, salt, optional vanilla, and enough cream or milk to make a spreadable buttercream. Level the cake layers if needed, fill and stack them, then frost the top and sides.