Preheat oven to 350°F.
In a medium bowl, pour boiling water over the TVP. Give it a stir and cover.
In a large pot, add cold water to the potatoes and bring to a boil. Turn it down to a simmer until fully cooked.
Heat olive oil in a large pan. Over medium-high heat, sauté the onions until soft and translucent.
Add the hydrated TVP, peas and corn to the onions. Sauté for 1 minute.
Season with ketchup, summer savoury, garlic powder, salt, pepper, and Worcestershire sauce. Turn down heat and continue to stir occasionally. Taste and adjust seasonings as needed.
Drain potatoes and return to pot. Add milk, butter and nutmeg. Beat with an electric hand mixer until smooth.
Add the egg to the potatoes and beat until incorporated.
Transfer the vegetarian ground round to an 8×8 casserole dish. Layer with the mashed potatoes.
Pop it in the oven for 5-10 minutes or broil.