Preheat oven to 400°F (200°C) to dry heating. - Remove the wellington from all the packaging. 3- Place the wellington on a cookie sheet and bake on middle oven rack for 30 to 35 minutes for a conventional oven and 20 to 25 minutes for a convection oven). Cook to a minimum internal temperature of 165°F (74°C). Let stand 3 minutes before serving. ***Cooking time may change with the oven and cooking mode.