Save a bit of the beaten egg for brushing the pastry (dilute with some water). Heat oven at 200C.
Mix beef, ketchup, the remaining egg, onion, half the garlic, the herbs and 50ml water until the meatloaf mix is well combined. Form into a sausage shape 15cm x 10cm and bake for 15 mins (consider cooking longer so the pastry doesn’t have to baked 50 mins). Let cool.
Fry the mushrooms in butter until not watery. Add the remaining garlic and fry just a little longer.
Roll the pastry, brush with egg, add a layer of mushrooms (aim to have them just under the meatloaf), add the meat in the center. Cut the pastry into strips from the meat outwards. Use those to criss-cross and cover the meatloaf in a ‘braided’ pattern. Brush with more egg.
Bake 50 mins. Cover with foil after about 30 mins if it’s browning too much.
Once the Wellington is almost done, pan fry the broccoli and flavor with sliced garlic.