Preheat the oven to 400 degrees F. Spray a 9-inch glass pie plate with cooking spray
Heat 3 tablespoons of the olive oil in large pot over medium-high heat. Add the anchovies, garlic and red pepper flakes and cook until fragrant, about 1 minute. Add the escarole and salt to the pan, cover and cook until wilted. Add the wine and cook for 1 minute. Remove and discard the garlic cloves. Let the escarole cool slightly, then place it in a large kitchen towel and gently ring out excess moisture. Transfer the greens to the bowl of a food processor. Add the olives, the lemon zest and juice, and the feta and process until finely chopped, about 30 seconds. Add the currants and pulse to combine.
Unroll the pie crusts. Use one to line a 9-inch pie pan, pressing it gently into the pan so there are no air bubbles and leaving some overhang around the edges. Brush the crust with the beaten egg, then spoon in the filling and distribute evenly. Cover with the second pie crust, tucking in and crimping the edges with your fingers or the tines of a fork. Cut three slits in the top crust to allow steam to escape. Brush the pie with the remaining 1 teaspoon olive oil and bake until golden brown and cooked through, about 40 minutes. Allow the pie to cool for at least 30 minutes before slicing.