Combine flour, sugar, zest, baking powder, baking soda, salt and butter in the bowl of a stand mixer fitted with the paddle attachment. Mix on low until butter is completely cut into the flour mixture.
Whisk together sour cream and heavy cream in a small bowl and add all of it to the dry ingredients at once. Mix on low until a dough forms. Add a little more heavy cream if it is dry.
Turn out onto plastic wrap and press to about ½ inch thick, wrap, and chill for 2 hours or until firm. Cut shortcakes. You can use any cutter that you’d like. I chose different sizes of a fluted cutter, but you could use a cookie cutter or even a glass. Chill again before baking. Can also be baked from frozen.
Preheat your oven to 350°F.
Prepare the blueberry filling:
Combine blueberries (it is better if they are thawed because they will cook faster and the shortcakes will be done at the same time), sugar, mandarin juice, and lemon juice. Taste. Adjust lemon juice or sugar as desired. Stir in cornstarch after tasting. Pour into baking dish. I used an 8 inch by 8 inch, but you could use a 9x9 or a round dish. I usually test my volume with the berries before I start.
Assemble and bake:
Place your shortcakes on top of the prepared filling and brush them with heavy cream and sprinkle with sugar. There can be some gaps or you can cover it almost completely. Place on a parchment lined baking sheet to eliminate sad oven clean-ups.
Bake 350°F for 35-50 minutes or until the blueberry filling is bubbling in the center and the top is golden brown.
Video
Notes
Technique - The key to a thicker filling here is to make sure it bakes long enough! Wait to take the cobbler out of the oven until after you can see the filling bubbling.Variations - You could experiment with different berries and citrus combinations! Just be sure to taste along the way to ensure the proper balance of ripeness, citrus, and sweetness. Storage - Store baked cobbler in a covered dish at room temperature or tightly wrapped in the refrigerator or freezer. Baked cobbler will keep for 3 days at room temperature, 10 days in the refrigerator or up to 3 months tightly wrapped in the freezer.