Preheat the oven to 400°F (200°C).
Prepare the sweet potatoes by peeling and cubing them.
Boil the sweet potatoes in a pot of salted water until tender, about 15 minutes.
Drain the sweet potatoes and mash them in a bowl.
Add olive oil, brown sugar, cinnamon, nutmeg, and lemon juice to the mashed sweet potatoes and mix well.
Roll out the pie crusts on a floured surface.
Cut out circles from the pie crust and place a spoonful of the sweet potato filling in the center.
Fold the crust over to create half-moon shapes and press the edges to seal.
Brush the tops with the beaten egg and sprinkle with sugar.
Bake in the preheated oven for 20-25 minutes or until golden brown.
Remove from the oven and let cool slightly before serving.