Step 1

In a large bowl, whisk together the flour, sugar, baking powder and salt. Using a pastry cutter, cut the butter into the flour mixture, until you have course crumbs. This can also be done with two knives or a food processor.

Step 2

Whisk the eggs lightly and combine with the buttermilk. Add to the flour mixture and stir until just moist.

Step 3

In a small bowl, mix together the gruyere, prosciutto, parmesan and green onion. Add this to the batter, then mix lightly. The dough will be sticky.

Step 4

On a lightly floured surface, turn the sticky dough out and knead lightly until all the cheese, prosciutto and green onion are incorporated into the dough. Roll the dough 3/4 inch thick. Cut out 3 inch squares, then cut diagonally to make triangles. You should have about 10 scones. Place the scones on a baking sheet lined with parchment or a silicone mat, and lightly brush with half and half. Sprinkle with sea salt.

Step 5

Place the scones in the freezer for 30 minutes. Meanwhile, preheat the oven to 400 degrees F.

Step 6

Once the scones are chilled, bake for 20 minutes, or until golden. Sprinkle with additional parmesan cheese and serve warm.