Preheat oven to 375 degrees.

In large bowl, whisk together eggs and egg whites. Add evaporated milk, salt, cayenne pepper, whisk to combine. Stir in bacon, cheese, and scallions. Pour the batter into the frozen pie shell.

Bake quiche in center of oven for 45-50 minutes or until the filling is puffed and the middle is slightly wobbly. (When you inset a thin knife into the center, it should come out moist; the filling will continue to set as it cools.) Cool on a rack for 10 minutes. Slice into 8 wedges and serve.