Whisk the eggs with the milk, then stir in bread crumbs, salt and pepper and allow the crumbs to soak in the milk for about 10 minutes until expanded.
In the meantime, saute the onion in butter until wilted and starts to brown.
Remove from the pan and stir into the egg mixture to combine.
Then add ground beef, parsley and ketchup and stir together until well mixed.
Line a loaf pan with baking parchment and fill with ground beef mixture, making sure that there are no air pockets as you pack the meat into the pan.
Bake in a preheated oven at 180°C for 40 minutes until nicely browned.
Turn the loaf out of the pan and remove all the parchment paper. With a pastry brush, coat the top and all sides of the meat loaf with the prepared glaze. Bake for another 10 minutes at 250°C until the glaze is thick and sticky.
Allow to rest at least 15 minutes before carving. Garnish with parsley and lemon zest.
In the meantime, prepare the mash. Boil chunky potatoes in about 3 cups of water for about 10-15 minutes until fluffy, drain off extra liquid and mash with butter until fluffy. Season with olive oil, salt and pepper to taste and lighten with milk.
Scoop into a serving plate with a slice of meat loaf and extra garnish and tomato ketchup if desired.