Preheat the oven to 375°F.
Set aside 2 apples of different types and peel, core, and slice all the other apples into 8 pieces each. Place the apple slices in a large bowl. Peel, core, and quarter the reserved 2 apples. Grate those apples through the large holes of a box grater into the bowl. Add the berries, brown sugar, tapioca starch, cinnamon, pepper, and salt over the apples. Gently toss to coat apples completely and mix the filling ingredients.
Lightly spray a 9 x 13-inch baking pan (or 3 quart oval pan) with cooking oil then place the baking pan on a rimmed baking sheet (just to catch any spillage).Pour into the prepared baking pan. Bake, uncovered, in the oven for 30 minutes. Pour the apples and any juices from the bowl into the prepared baking pan. Bake, uncovered, for about 30 minutes.
While the apples are baking, combine the flour, sugar, baking powder, baking soda, and salt in a large bowl. Stir vigorously with a balloon whisk until the ingredients are evenly distributed. Drizzle the butter over the dry ingredients and toss with a fork until small clumps form. Drizzle the buttermilk over the mix and toss with a fork until a soft, sticky dough forms.
Dump the dough onto a clean surface generously dusted with flour. Press the dough into a 9 x12-inch rectangle, dusting your hands as often as needed to keep the dough from sticking.
Combine both sugars, cinnamon, pepper, salt, and butter in a large bowl and stir until a paste forms.
Stir in diced strawberries.
Spread the sugary strawberry mixture over the cobbler dough. Roll up the dough from the long side, using a flat spatula or bench scraper to help scrape the sticky dough from the surface. You should have a 12-inch-long log.
Cut the log into twelve 1-inch-thick disks.
Once the apple filling has baked for 30 minutes, pull the pan out of the oven. Place the cobbler disks on top of the apples, swirl side up. Brush the tops with the melted butter and sprinkle the sugar on top. Bake until the filling is thick and bubbly and the cobbler top has turned golden brown, 30 to 35 minutes more.
Adapted from my cookbook Marbled, Swirled, and Layered.