In a large bowl, whisk flour, ¼ cup sugar, baking powder, and salt. Add butter and combine with fingers until small crumbles form.
Add milk and mix into dough. Move dough to refrigerator for 20-30 minutes. Heat remaining sugar, blueberries, lemon juice, and orange juice in a 12" cast-iron skillet on high heat.
Stir frequently until sugar dissolves.
Remove pan from heat and drop 2 inch balls of biscuit dough into berries.
Sprinkle dough with sugar and transfer skillet into oven for 25 minutes. Serve with vanilla ice cream.
Recipe by Rachel Schultz at https://rachelschultz.com/2012/09/05/new-england-blueberry-slump/