Preheat the oven to 350 degrees F. Grease or spray with nonstick cooking spray a standard 9x5 loaf pan.
Whisk together the flour, sugar, baking powder, baking soda and salt in a medium mixing bowl.
In another bowl, combine the cheeses. Reserve about 1/3 cup of this mixture for topping and pour the rest into the flour mixture. Gently stir to coat.
In a separate bowl, whisk together the butter or oil, buttermilk, egg, herbs and garlic.
Pour the liquid ingredients over the dry ingredients. Gently stir and fold the ingredients until all the flour has been incorporated and a wet batter is formed, then gently fold in the sun dried tomatoes. Be careful not to over-mix.
Pour the batter into the prepared pan, spreading to the edges. Sprinkle remaining 1/4 cup of Mozzarella cheese on top of the batter, if desired.
Bake in the preheated 350 degree oven for 45-50 minutes. When finished, the loaf should be domed and golden, and a toothpick inserted into the center should come out clean.
Cool in the pan for 15 minutes before removing, slicing and serving.
Wrap cooled loaves tightly in plastic wrap and store at room temperature. For freezer storage, wrap in plastic and aluminum foil and frozen for up to three months.