Crack an egg into a small bowl and add a splash of water, then whisk to combine. Use a pastry brush to brush the top of the mince pies with the egg wash.
Bake for 10-20 minutes, depending on the size of your baking pan. I find the smaller tart size pies take 10-13 minutes while the cupcake size ones take 14-18 minutes, you want golden brown!