Add the 800 grams blueberries and 70 grams granulated sugar into a pan and heat over medium-low heat until the berries begin to release some juice. Turn the heat up to maintain a simmer and cook until the fruit is tender and their juices start to thicken just a bit (about 20 minutes).
While the berries are cooking wash the 1 lemon well and shave the zest into a small bowl using a Microplane. Juice the lemon into the same bowl (you should have around 2 tablespoons of juice). Stir the 2 teaspoons potato starch into the mixture.
Prepare the biscuit dough by whisking together the 130 grams all-purpose flour, 27 grams evaporated cane sugar, 2 teaspoons baking powder, ¼ teaspoon baking soda, and ¼ teaspoon coarse salt.
Use a fork or pastry blender to cut the cold 60 grams cultured unsalted butter into the flour mixture until a crumbly dough forms. Refrigerate until the berries are ready.
Preheat the oven to 400 degrees F (200 C).
When the blueberry filling has reached the consistency of maple syrup (the real kind), add the lemon and starch mixture and stir to combine. Transfer the filling to a 9-inch pie dish (or you can make the cobbler in the pan you cooked the blueberries in).
Finish the biscuit topping by whisking the 1 teaspoon vanilla extract into the ⅓ cup plain yogurt and stirring this into the flour mixture until the dough barely comes together. Do not overmix or the biscuits will end up tough.
To assemble the cobbler, divide the biscuits into 5-8 balls and roll the top surface in the 2 tablespoons coarse sugar. Drop the biscuits on the blueberry filling with the sugared side up.
Place the cobbler on a baking sheet and bake until the biscuits are cooked through and golden brown on top (about 15-20 minutes).
Serve the blueberry cobbler warm with ice cream or whipped cream.