Save This hearty Thanksgiving Sweet Potato Pasta Gratin has transformed my holiday table from predictable to extraordinary. It strikes the perfect balance between comfort food and festive elegance, bringing together the sweetness of sweet potatoes with the earthiness of sage in a creamy, cheesy embrace.
I first created this recipe when my vegetarian sister announced she was joining us for Thanksgiving. Three years later, it has become more requested than the turkey itself, with everyone fighting over the crispy cheese corners.
Ingredients
- Sweet potatoes: provide natural sweetness and beautiful color while adding nutritional value that regular potatoes lack
- Yellow onion: creates an aromatic foundation when sautéed with butter until translucent
- Fresh sage: brings quintessential Thanksgiving flavor that dried simply cannot match
- Short pasta like rigatoni or penne: catches the creamy sauce in its ridges and hollows
- Gruyère cheese: melts into silky perfection while adding complex nutty flavor
- Parmesan: adds salty depth and creates that irresistible golden crust
- Fresh breadcrumbs: absorb butter while toasting to create textural contrast against the creamy interior
- Heavy cream: enriches the sauce for a truly indulgent holiday dish
- Nutmeg: enhances the sweetness of both the cream and sweet potatoes without being overtly noticeable
Instructions
- Prepare the base:
- Preheat your oven to 190°C and generously butter your baking dish. This prevents sticking and adds flavor to the edges that will become deliciously caramelized during baking.
- Cook the pasta:
- Boil your pasta for exactly 2 minutes less than the package instructions indicate. The pasta will continue cooking in the oven, and this undercooking ensures it maintains structure rather than becoming mushy in the final dish.
- Create the flavor foundation:
- Melt butter in a saucepan over medium heat until it begins to foam slightly. Add your finely chopped onion and cook until translucent and soft but not browned, about 4 minutes. This develops sweetness in the onion without bitter notes.
- Build the aromatics:
- Add minced garlic and chopped sage to the softened onions, stirring constantly for one minute. The heat releases the essential oils in both ingredients, but be careful not to brown the garlic which would introduce bitterness.
- Make the béchamel:
- Sprinkle flour over the aromatic mixture and cook for a full minute, stirring constantly to eliminate raw flour taste. Gradually whisk in milk and cream, starting with just a small amount to create a smooth paste before adding the remaining liquid. This technique prevents lumps from forming.
- Thicken the sauce:
- Bring the mixture to a gentle simmer, stirring frequently with a whisk to prevent scorching on the bottom. The sauce will thicken noticeably after about 5 minutes, coating the back of a spoon.
- Season and add cheese:
- Remove from heat before stirring in nutmeg, salt, and pepper. Then incorporate half of each cheese, stirring until completely melted. The residual heat melts the cheese while preventing it from becoming stringy or separating.
- Layer the components:
- Create your first layer with half the thinly sliced sweet potatoes, followed by half the pasta, then half the cheese sauce. Repeat these layers, ensuring the sweet potato slices are arranged in a somewhat overlapping pattern for even cooking.
- Add final cheese layer:
- Sprinkle the remaining Gruyère and Parmesan evenly across the top to create a golden, cheesy crust during baking.
- Prepare the crispy topping:
- Mix fresh breadcrumbs with olive oil and optional parsley until each crumb is lightly coated. This oil helps the breadcrumbs brown evenly without burning.
- Bake in stages:
- Cover the dish with foil and bake for 25 minutes to cook the sweet potatoes through. Then remove the foil and continue baking for 15-20 minutes until gloriously golden and bubbling around the edges.
- Rest before serving:
- Allow the gratin to rest for a full 10 minutes before serving. This critical step helps the sauce set slightly so each portion holds its shape when served.
Save This dish holds a special place in my heart because it was born from necessity but became tradition. The first year I made it, I had run out of regular potatoes and improvised with sweet potatoes from our garden. The beautiful orange color against the creamy sauce made such a stunning presentation that everyone insisted it return every year.
Make Ahead Magic
This gratin actually improves when made ahead. Assemble the entire dish up to the point of baking, cover tightly with plastic wrap and refrigerate for up to 24 hours. Remove from the refrigerator 30 minutes before baking to take the chill off, then bake as directed, adding about 10 minutes to the covered baking time. The flavors meld beautifully overnight, and having it ready to pop in the oven makes holiday cooking much less stressful.
Clever Substitutions
Dairy free version. Replace butter with olive oil, milk and cream with unsweetened almond or oat milk thickened with an extra tablespoon of flour, and cheese with dairy free alternatives that melt well.
Gluten free adaptation. Use your favorite gluten free pasta and replace the all purpose flour with cornstarch for the sauce about half the amount. For the topping, crushed gluten free crackers or cornflakes mixed with a bit of olive oil create a wonderful crunch.
Root vegetable variations. While sweet potatoes are the star, this recipe works beautifully with butternut squash, delicata squash, or even a combination of root vegetables like parsnips and carrots. Just ensure they are sliced to similar thickness for even cooking.
Serving Suggestions
This versatile dish works equally well as a vegetarian main course or as a substantial side dish alongside roasted turkey or ham. For a complete vegetarian Thanksgiving menu, serve it with roasted brussels sprouts, cranberry sauce, and a crisp green salad dressed with a light vinaigrette to cut through the richness.
When serving as a main course, a simple garnish of fresh herbs like additional chopped parsley or fried sage leaves adds a professional touch and bright contrast to the rich dish.
For wine pairing, the creamy texture and sweet notes from the potatoes work beautifully with a lightly oaked Chardonnay or, for red wine lovers, a fruit forward Pinot Noir that won't overwhelm the delicate flavors.
Save This dish is a showstopper that tastes as good as it looks.
Recipe FAQ
- → Can I use a different cheese instead of Gruyère?
Yes, sharp cheddar works well in place of Gruyère, offering a similar melt and flavor depth.
- → How can I make this dish gluten-free?
Swap in gluten-free pasta and use a gluten-free flour blend in the sauce to keep it safe for gluten sensitivities.
- → Can I add other vegetables?
Absolutely—sautéed mushrooms or spinach can be layered in for extra flavor and nutrition.
- → Is it possible to make ahead and reheat?
Yes, assemble and bake in advance. Reheat gently in the oven until hot and bubbly before serving.
- → What wine pairs well?
A crisp Chardonnay or light Pinot Noir complements the creamy, cheesy flavors beautifully.
- → Do I need to peel the sweet potatoes?
For the best texture, peel the sweet potatoes before slicing and layering them in the dish.