In a large skillet, brown the onion and ham in the oil. Season with salt and pepper. Let cool.
In a large bowl, combine the eggs, milk, and cream. Season with salt and pepper. Add the remaining ingredients and stir to combine. Spoon into a 33 x 23-cm (13 x 9-inch) baking dish. Cover with plastic wrap and refrigerate for 4 to 8 hours. Pressed for time, let the bread soak for only 1 hour.
With the rack in the middle position, preheat the oven to 180 °C (350 °F).
Remove the plastic wrap and bake for about 1 hour or until the centre of the strata is cooked. Allow to cool for 10 minutes and serve with a green salad.
Whole cooked ham will keep for up to 8 days in the refrigerator while sliced ham will only keep for 3 to 4 days. You can freeze ham for up to 2 months but its texture will be much less interesting and will be water logged.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.