Equipment
* optional
Ingredients
Gratin Base
- 1200 g butternut squash, peeled, seeded, and sliced 3mm thick
- 480 ml heavy cream
- 2 garlic, smashed
- 3 fresh sage, whole sprigs
- 1 g nutmeg, freshly grated
- 120 g gruyère cheese, grated
- 5 g salt
- 1 g black pepper, freshly ground
Bacon & Black Walnut Crisp
- 150 g thick-cut bacon, diced
- 60 g black walnuts, roughly chopped
- 40 g panko breadcrumbs
- 30 g parmesan cheese, finely grated
- 2 g fresh thyme, leaves stripped and chopped
Nutrition (per serving)
Method
Preheat the oven to 190°C (375°F). Grease a 9x13 inch baking dish generously with butter.
In a small saucepan, combine heavy cream, smashed garlic, sage sprigs, nutmeg, salt, and pepper. Bring to a bare simmer over medium heat, then remove from heat and let infuse for 10 minutes. Remove garlic and sage before using.
Arrange half of the sliced squash in the prepared baking dish in overlapping shingles. Sprinkle with half of the Gruyère cheese. Layer the remaining squash on top. Pour the infused cream mixture evenly over the entire dish.
Cover the dish tightly with foil. Bake for 40 minutes, or until the squash is tender when pierced with a knife.
While the gratin bakes, fry the diced bacon in a frying pan over medium heat until crisp. Remove bacon with a slotted spoon to a paper towel, keeping 15ml (1 tbsp) of rendered fat in the pan.
Add the panko breadcrumbs and chopped black walnuts to the pan with the reserved bacon fat. Toast over medium heat for 2-3 minutes until golden. Remove from heat and toss in a bowl with the cooked bacon, parmesan, and fresh thyme.
Remove the foil from the gratin. Scatter the bacon-walnut mixture evenly over the top. Return to the oven and bake uncovered for another 15-20 minutes until bubbling and deeply browned.
Remove from the oven and let rest for at least 15 minutes before serving. This allows the sauce to thicken and the layers to set.
Chef's Notes
- Black walnuts have a bold, distinctively earthy flavor compared to English walnuts. If they are too strong for your palate, use a 50/50 mix or substitute entirely with English walnuts or pecans.
- Do not skip the resting period. If you cut into the gratin immediately, the cream sauce will be runny. Resting allows the starches to stabilize the emulsion.
- If you don't have a mandoline, take your time to cut the squash as uniformly as possible. Varying thicknesses will result in uneven cooking.
- For a richer holiday presentation, you can submerge the sage leaves in the frying oil/bacon fat for 10 seconds to create crispy sage garnishes.
Storage
Refrigerator: 4 days — Cover tightly; the topping may lose crispness.
Freezer: 2 months — Bake from frozen at 175°C (350°F) until heated through.
Reheating: Reheat in a 175°C (350°F) oven for 15-20 minutes to re-crisp the topping.
