Preheat oven to 400 degrees F.
Mix eggs, flour, milk, vanilla, zest, and salt in a food processor until blended.
Put one tablespoon butter in each of four small cast-iron skillets; place in oven until melted. Pour equal portions into each skillet and return to oven for 20 minutes. Reduce heat to 350 degrees F and continue cooking 5-7 minutes longer.
Remove from oven and dust with powdered sugar. Top each with ¼ cup curd and blackberries and serve.