In a large bowl combine flour, coconut oil and butter. Using a pastry blender, cut in the butter and coconut oil until the mixture resembles large peas. Adding 1 tablespoon of ice water at a time, knead dough until it comes together in a large ball. Wrap dough in plastic wrap and refrigerate for 1 hour or overnight.
Preheat oven to 350 F. In a small pot set over medium heat combine the blueberries, panela, rum and cornstarch. Cook for 5 minutes, until blueberries are soft, some have popped and a thicker filling has formed.
Roll out dough on a well-floured surface until 1/8-inch thick. Cut out 4-inch discs, combine scraps, knead again and repeat until all the dough has been used.
Using one disc at a time, place 2 to 3 tablespoons of blueberry filling onto center of disc. Wet your finger in a small bowl of water and run it on the edges of the disc. Fold over top to bottom and crimp edges. Repeat with remaining filling and discs.
Place discs on the prepared baking sheet. Bake until the empanadas are golden brown and the filling begins to leak out, 10 to 15 minutes.