I’m not a baker and I’m not an expert – this is just what I’ve learned along the way.
For a really golden, dark, shiny finish, glaze your pie with egg yolk and just a little sprinkle of water. Save the white for some protein-rich scrambled eggs tomorrow. If you don’t need the gloss, a whole beaten egg is fine.
If you really want to go to town, paint on one layer, pop the pie back in the fridge for 5–10 minutes, then paint on a second. Obviously, I can never be bothered! Even so – look at that beautiful golden crust. I’m feeling very smug.