How to Make It
Preheat the oven to 375°. Butter a 9-inch round cake pan. Spread the blueberries in the prepared pan and sprinkle with 1 1/2 tablespoons of the sugar. In a medium bowl, mix the flour with the baking powder, baking soda, and salt.
In a standing mixer fitted with the paddle, beat the butter with the remaining 3/4 cup of the sugar at moderately high speed until fluffy, about 2 minutes. Scrape the side of the bowl. Add the buttermilk, egg, lemon zest and vanilla and beat at medium speed until combined (the mixture will be lumpy). Add the flour mixture and beat at moderately low speed until just combined.
Spread the batter over the blueberries. Bake for about 45 minutes, until the top is golden and a toothpick inserted into the cake comes out clean. Transfer the cake to a rack and let cool for 15 minutes. Run a small knife around the edge of the cake, invert it onto a rack and let cool completely, about 1 hour. Cut into wedges and serve.
Vanilla ice cream, whipped cream or crème fraîche.