Spinach and Leek Gratin with Roquefort Crumb Topping

Here's a side dish that is a bit fancier than plain 'ol spinach. But it's still really easy. I made it even easier by wilting the spianch and then just adding the butter and leeks to the same pan. I also substituted goat cheese for the blue...adding it to the veggie mixture and letting melt in slightly before putting it in the baking dish and topping with breadcrumbs.

Spinach and Leek Gratin with Roquefort Crumb Topping
Serves eight.
From Bon Appetit.

5 tablespoons butter, divided
3 1/2 tablespoons horseradish Dijon mustard, divided
2 1/3 cups fresh breadcrumbs from crustless French bread
1 cup crumbled Roquefort cheese (generous 4 ounces)
3 9-ounce bags spinach leaves
1 8-ounce leek, halved lengthwise, thinly sliced crosswise (about 3 cups)
3/4 cup heavy whipping cream

Preheat oven to 400°F.

Melt 3 tablespoons butter in medium skillet over medium-high heat. Mix in 2 tablespoons mustard, then breadcrumbs. Sauté until breadcrumbs are golden, about 5 minutes. Cool briefly.

Mix in cheese.

Toss 1 1/2 bags spinach in large nonstick pot over high heat until wilted, about 3 minutes. Transfer to sieve set over bowl. Repeat with remaining spinach. Press on spinach to drain.

Melt remaining 2 tablespoons butter in same pot over medium-high heat. Add leek; sauté 4 minutes. Add cream, remaining 1 1/2 tablespoons mustard, and spinach. Toss until thick and blended, about 2 minutes. Season with salt and pepper. Transfer to 7x11-inch baking dish. Top with breadcrumb mixture. Bake until bubbling, about 10 minutes.