Preheat the oven to 350°F. Lightly grease and flour a 9-inch loaf pan.
Whisk together 1 cup + 2 tablespoons of flour, the baking powder, baking soda, and salt in a medium bowl. Set aside.
Beat ¾ stick of butter and the sugar in the bowl of an electric mixer on medium speed for 3 to 4 minutes, until light and fluffy. Add the eggs, one at a time, blending well after each addition. Add the buttermilk, lemon zest, and vanilla extract and mix until well combined. With the mixer on low speed, add the flour mixture in three additions, blending until just incorporated. Toss the blueberries with the remaining 2 tablespoons of flour and gently fold into the batter.
Pour the batter into the prepared pan and smooth the top. Bake for about 1 hour, until a cake tester comes out clean. Remove from the oven and let cool for 20 minutes. Invert the cake onto a wire rack and let cool completely.
Place a large griddle over medium heat. Melt the remaining ½ stick of butter in a small saucepan. Cut the blueberry bread into 8 even slices. Brush the butter over both sides of each bread slice. Grill the bread for 3 to 4 minutes per side, until lightly toasted. Top each piece of bread with a dollop of lemon curd and serve.