Preheat the oven to 350 degrees. Coat an 8 × 8 baking dish with cooking spray.
Cream the butter, sugar and lemon zest together with a mixer until creamy and smooth. Add the egg and vanilla and beat until combined.
Mix the flour together with the baking powder and salt until well mixed.
Add the flour mixture to the butter mixture a little at a time alternating with the buttermilk. Fold in most of the raspberries gently. Side note: The batter will be very thick.
Spread batter into the pan evenly. Gently push the remaining few raspberries into the top of the cake in places that need one.
Sprinkle the 1-2 tablespoons of sugar evenly on top of the batter.
Place into the oven and bake for 40-45 minutes or until a tester inserted into the center of the cake comes out clean.
Let it cool for at least 10-15 minutes before cutting and serving. Enjoy!