Makes 12 scones
3/4 cup semisweet chocolate chunks
Preheat the oven to 400 F and line a baking sheet with parchment.
In the bowl of an electric mixer fitted with the paddle attachment, sift together the flour, baking soda, baking powder and salt. Add sugar and mix slowly to combine.
Add the butter to the mixer and blend on low speed until just combined and the butter is still in pea-sized pieces. Add the buttermilk, lemon zest and chocolate chunks and mix over low speed until the dough just comes together.
Place the dough onto a floured surface and shape it into a long rectangle about 18 inches long, 5 inches wide and 1.5 inches thick.
Brush the dough with melted butter and sprinkle very generously with sugar. Cut the dough into 6 rectangles, and then cut each rectangle into 2 triangles. Transfer scones to baking sheet. Bake until tops are lightly browed, 20 to 30 minutes (depending on the size of the scones). Serve warm.