Preheat the oven to 375°F. Combine the buttermilk and egg in a medium bowl, stirring with a whisk. Spray baking sheet with cooking spray.
Combine the flours with the baking powder and salt, in a large bowl, stirring with a whisk.
Squeeze all the excess moisture from the zucchini with a paper towel, you should wind up with 1 cup after it’s all squeezed. In a bowl combine the zucchini, sun dried tomatoes, cheese and rosemary.
Cut in the chilled butter with a pastry blender, or you could use 2 knives, until the mixture resembles coarse meal. Gently fold in the cheese, zucchini, sun dried tomatoes and rosemary. Add milk mixture, stirring just until moist, without overworking the dough.
Place dough onto a floured surface and knead lightly four times with floured hands. Form dough into an 10-inch circle onto the baking sheet, about 3/4″ thick, you may need to sprinkle a little more flour on top if it’s too sticky. Using a knife, cut dough into 12 wedges all the way through.
Brush egg white over dough. Bake until golden, about 20 – 22 minutes, depending on your oven.
Serve warm and enjoy!