Instead of potatoes, reach for different vegetables for this classic holiday side dish.
Then all you have to do the day of is top it and bake.
Cook, stirring occasionally, until onion is translucent, 3 to 4 minutes.
Credit:Brian Woodcock; Food Stylist: Julian Hensarling; Prop Stylist: Christina Daley
Stir in flour; cook, stirring constantly, until flour coats vegetables, about 1 minute.
Stir in cream, milk, mustard, pepper, nutmeg, and remaining 3/4 teaspoon salt.
Remove from heat; transfer 2 cups of the cream mixture to a medium bowl.
Layer half of butternut squash rounds over remaining cream mixture in skillet, overlapping slices slightly.
Top with 1 cup of the reserved cream mixture and 1/4 cup of the Parmesan.
Repeat with remaining cream mixture and squash and 1/4 cup of the Parmesan.
Reduce oven temperature to 400F.
Remove and discard aluminum foil; top evenly with breadcrumbs and remaining 3/4 cup Parmesan.
Bake until sauce is bubbling and cheese is golden brown around the edges, 20 to 25 minutes.
Garnish with reserved fennel fronds just before serving.
