1/2 teaspoon baking powder
1/2 teaspoon baking soda
1/4 teaspoon salt
1/2 stick (4 ounces) unsalted butter, softened
2/3 cup plus 1 tablespoon sugar, divided*
1/2 teaspoon vanilla extract
1 large egg
1/2 cup well-shaken buttermilk
1 cup fresh blueberries
Preheat oven to 400ºF. Butter a 9-inch cake pan and line with parchment; butter parchment.
Whisk together flour, baking powder, baking soda, and salt in a medium bowl. With a standing or hand mixer, beat butter with the 2/3 cup sugar until light and fluffy, about 2 minutes. Add vanilla extract and egg, beating thoroughly. Turn speed to low and alternate adding flour mixture and buttermilk, mixing until just combined. Spread batter into prepared pan, smoothing the top. Scatter the raspberries evenly over the top (no need to push them down) and sprinkle with the 1 tablespoon sugar.
Bake at 400º for about 20-25 minutes or until cake is golden and a toothpick inserted in the center comes out clean. Cool in pan 15 minutes, then transfer to a rack to cool completely.
*I forgot to sprinkle the cake with sugar and it wasn't missed
**I used 1 teaspoon of lemon as I like the lemon flavor to be more pronounced when combined with blueberries