This recipe I got from the Smitten Kitchen blog which I love... (; She adapted it from Gourmet.)

I basically followed her recipe, but used frozen raspberries - first time, I let them defrost. Mistake! Use them frozen, they still cook perfectly.

I find this very yummy and it is possibly the most ridiculously-easy cake ever! 

1 cup all-purpose flour
1/2 teaspoon baking powder
1/2 teaspoon  baking soda
1/4 teaspoon salt
56 grams unsalted butter, softened
2/3 cup plus 1 1/2 tablespoons sugar, divided (I used caster sugar)
1/2 teaspoon pure vanilla extract
1/2 teaspoon finely grated lemon zest (I used about 2 tsp)
1 large egg
1/2 cup well-shaken buttermilk (bought or made from milk by adding 1/2 Tbsp of vinegar or lemon juice to 1/2 C milk and let it stand for 10 mins)
1 cup raspberries (fresh or frozen fine)

Preheat oven to 200C with rack in middle. Butter and flour a 9-inch round cake pan and line with paper (first attempt, without paper, was a stick-to-the-bottom hassle!)

Whisk together flour, baking powder, baking soda, and salt and set aside. In a larger bowl, beat butter and 2/3 cup sugar with an electric mixer at medium-high speed until pale and fluffy, then beat in vanilla and zest, if using. Add egg and beat well.

At low speed, mix in flour mixture in three batches, alternating with buttermilk, beginning and ending with flour, and mixing until just combined.Spoon batter into cake pan, smoothing top. Scatter  raspberries evenly over top, or place them carefully if you are a bit OCD like me. And sprinkle with remaining 1 1/2 tablespoons sugar.

Bake until cake is golden and a wooden pick inserted into center comes out clean, 20 to 25 minutes (seriously, this is really quick!). Cool in tin for 10 minutes, then turn out onto a rack and cool