In a large mixing bowl, whisk together flour, sugar, brown sugar, baking powder, baking soda, and salt. Set aside.

In a small bowl, whisk together 1 cup of the heavy cream, egg, and vanilla extract.

Add the pieces of cold butter to the dry ingredients and lightly toss until all of the pieces are coated. Using a pastry cutter or your fingers, quickly cut the butter into the flour mixture until the mixture is pebbly. You want there to still be little chunks of butter, about pea size. Don't over mix.

Pour the cream mixture over the dry ingredients and use a fork to gently stir together. Don't over stir, the mixture will be wet and sticky. Stir in the chocolate chips. Still in the bowl, knead the dough a few times until the dough comes together.

Place the scone dough on a lightly floured surface. Gently pat and shape the dough into a 3/4-1-inch thick circle. Use a sharp knife to cut the scones into 8 even triangles. Place the scones on the prepared baking sheet and brush with the remaining heavy cream. Sprinkle the scones generously with turbinado sugar. If the scones are soft and have heated up too much, place the baking sheet with the scones in the freezer for 15-20 minutes before baking. I usually do this just to be safe.

When ready to bake, place the baking sheet in the oven, on the middle rack, an bake for 17-22 minutes or until the tops and edges are golden brown and the scones are set but still slightly soft in the center. Remove from the oven and let the scones cool on the baking sheet for 5 minutes. Transfer to a wire cooling rack and cool completely.