Every Christmas morning I serve breakfast to all of my family. Each year I like to come with at least one new dish to serve. This is this year's new dish which sounds decadent, creamy and glorious - I think it will become my favorite new breakfast casserole.
Heat oven to 425 degrees. Coat a 9x13 pan or 8, 16oz baking dishes with oil. Place english muffin pieces on a large rimmed baking sheet and bake until lightly golden brown, 12-15 minutes; transfer to the prepared baking dish. Reduce heat to 350 degrees.
Meanwhile, heat oil in large skillet over medium heat. Add the leek and cook, stirring occasionally, about 4 minutes. Increase the heat to medium-high, add the bacon and cook, stirring occasionally, until beginning to brown about 4-5 minutes more. Spoon the mixture over the english muffins.
In a large bowl, whisk together the whole eggs, milk, dry mustard, chives, 1 1/2 cups cream and 1/2 tsp each cayenne, salt and pepper. Pour the egg mixture over the leek-bacon mixture and bake until casserole is puffed, golden brown and just set, 40-45 minutes (about 25 minuts if using individual dishes)
Ten minutes before the casserole is finished, make the hollandaise sauce. Melt butter in microwave. In a metal or glass bowl, whisk together the egg yolks, lemon juice, Dijion mustard, remaining 1/2 cup cream, 1/4tsp cayenne and 1/2tsp salt. Place the bowl over (but not in) a saucepan of simmering water and cook, whisking constantly until mixture is thick enough to coat the back of a spoon, about 2-3 minutes. Reduce heat to low. Still whisking constantly, gradually add the meltd butter. Serve with casserole.