- Heat a sauté pan over medium heat and add the butter. Once melted, add the leeks and cook, stirring often, until wilted but not brown, about 15 minutes. Set aside to cool. While cooking the leeks, preheat the oven to 350°F (180°C) and butter an 8-cup (2 L) baking dish.
- Whisk the eggs and mustard in a large bowl by hand until the eggs are well blended. Whisk in the milk (or whipping cream), salt and pepper, and then add the cubed bread, stirring well to fully coat. Let sit for about 10 minutes to allow the bread to soak up some of the liquid.
- Stir the ham, cheese and cooked leeks into the bread mixture and pour this mixture into the prepared pan. Bake the strata, uncovered, for 60 to 75 minutes, until the strata inflates a little and springs back when pressed in the centre. Remove the strata from the oven and cool for about 15 minutes on a cooling rack.
- To serve, spoon the strata into individual bowls or plates.
Strata is an easy make-ahead meal. Assemble it the day before, refrigerate overnight and add 15 to 20 minutes to the cook time to factor in that the entire dish is cold.
Recipe from Set for the Holidays with Anna Olson, Appetite by Random House, 2018