Peel the potatoes and cut into 1/2-inch cubes and place in a large pot and cover with cold water.

Cover and cook over high heat and bring to a boil. Once boiling, uncover, decrease the heat to medium and cook until potatoes are tender, about 10 to 15 minutes.

Place the half & half and butter in a microwave-safe bowl and microwave until warmed through, about 35 seconds.

Drain the potatoes in a colander and then return to the pot. Mash the potatoes and add the half & half, butter, salt and pepper and continue to mash until smooth. Stir in the yolk until well combined.

Preheat the oven to 400 degrees F.

While the potatoes are cooking, prepare the filling by adding the canola oil to a 12-inch pan and set over medium-high heat.

Add the onion and carrots and saute just until they begin to take on color, approximately 3 to 4 minutes.

Add the garlic and stir to combine.

Add the sausage, salt, and pepper and cook until browned and cooked through to render the fat a little, approximately 7 minutes.

Sprinkle the meat with the flour and toss to coat, continuing to cook for another minute.

Add the chicken broth, Worcestershire sauce, rosemary, thyme, and stir to combine.

Bring to a boil, then reduce the heat to low, cover and simmer slowly 10 to 12 minutes or until the sauce is thickened slightly.

Add the corn and peas to the sausage mixture and spread evenly into an 11 by 7-inch baking dish.

Top with the mashed potatoes, starting around the edges to create a seal to prevent the mixture from bubbling up and smooth with a rubber spatula.

Bake for 25 minutes or just until the potatoes begin to brown. Remove to a cooling rack for at least 15 minutes before serving.