1. In a large bowl, stir together 2 3/4 cups flour, chocolate chips, baking powder, and baking soda.
2. In another bowl with a mixer on medium-high speed, beat 1/2 cup butter with 1/2 cup sugar until fluffy; beat in egg. Stir in buttermilk and liqueur.
3. Scrape butter mixture into dry ingredients; stir just until evenly moistened. Sprinkle 1 teaspoon sugar over bottom of a buttered 9-inch pie pan. Scrape dough into center of pan; sprinkle another 1 to 2 teaspoons sugar onto dough. Pat gently into an 8-inch-wide round. With a floured knife, cut through dough to pan to make 8 equal triangles.
4. Bake in a 350° oven until scones are golden brown and just begin to pull from pan sides, 50 to 55 minutes.
5. Slide a wide spatula under scones, then slip out onto a rack; let cool 10 minutes. Cut wedges apart and serve.