Preheat the oven to 350°F / 175°C. Mix ½ cup of canola oil, ½ cup of melted butter, and ½ teaspoon of salt, then add ½ cup of hot water.
Stir in 3 cups of all-purpose flour, ½ cup at a time, until a soft, oily dough forms, without overworking it.
In a food processor, pulse 170g of crumbled feta, 170g of kashkaval, ¼ cup of chopped parsley, 2 large eggs, and ¼ teaspoon of black pepper into a light paste.
Roll out the dough a portion at a time into thin squares and cut each into quarters. Put 1 tablespoon of filling in the center of each piece, fold it into a triangle, and pinch the edges to seal.
Arrange on a baking sheet and brush with 1 large beaten egg. Bake for 40-45 minutes, until golden.
