Combine flour, salt, and baking powder in a large bowl; cut in lard and butter with a pastry blender. Stir in egg and enough water to make a soft dough. Cover and chill 30 minutes.
Divide dough into four portions. Place one portion of dough on a lightly floured surface. Chill remaining dough.
Roll dough to 1/8-inch thickness; cut dough into 6 circles using a 3 1/2-inch round cookie cutter, re-rolling dough if necessary.
Place 2 teaspoons Spinach Filling in center of circle; brush edges lightly with water. Fold edges over, and press firmly with a fork to seal. Set aside. Repeat with remaining dough circles and filling.
Pour oil to a depth of 2 inches in a Dutch oven; heat oil to 365°. Fry empanadas, in batches, 2 to 3 minutes or until golden. Drain on paper towels. Serve immediately.