Butternut Squash Frittata
This Butternut Squash Frittata is a hearty, naturally gluten-free egg dish that works beautifully for brunch, dinner, or meal prep. Roasted butternut squash brings caramel-like sweetness, while sautéed onion, garlic, wilted spinach, and nutty Gruyère cheese round out every bite. Made entirely in one oven-safe skillet using a simple stovetop-to-oven technique, it delivers perfectly set edges, a custardy center, and a golden, bubbly top with minimal effort.
Equipment
- 10-inch cast iron skillet Or any oven-safe skillet; 12-inch also works
- Rimmed baking sheet For roasting the butternut squash
- Large mixing bowl For whisking the egg mixture
- Whisk
- Box grater For grating Gruyère cheese fresh
- Cutting board
- Sharp knife
- Vegetable peeler For peeling the butternut squash
- Silicone spatula
- Oven mitts
- Instant-read thermometer (optional) For checking doneness; center should read 165–170°F
Ingredients
For the Roasted Squash
- 2 cups butternut squash about 300g; peeled and cut into ½-inch cubes (approximately 1 small squash)
- 1 tbsp extra virgin olive oil 15ml
- ¼ tsp kosher salt for seasoning squash
- ¼ tsp smoked paprika for seasoning squash
- black pepper pinch, for seasoning squash
For the Egg Mixture
- 8 large eggs room temperature
- ¼ cup whole milk 60ml; or heavy cream for a richer frittata
- 1 cup Gruyère cheese about 100g; freshly grated; divided — ⅔ stirred into eggs, ⅓ reserved for topping; substitute feta or sharp cheddar
- ¼ tsp smoked paprika for the egg mixture
- ¼ tsp kosher salt for the egg mixture; plus more to taste
- ¼ tsp black pepper
- red pepper flakes pinch; optional, for gentle background heat
For the Sauté
- 1 tbsp extra virgin olive oil 15ml; for sautéing
- 1 medium yellow onion thinly sliced
- 3 cloves garlic minced
- 2 cups fresh baby spinach about 60g; loosely packed
- 1 tsp fresh thyme leaves or ½ tsp dried thyme
For Garnish
- fresh parsley chopped; or thinly sliced fresh chives
Instructions
- Preheat oven to 400°F (200°C). Toss cubed butternut squash with 1 tbsp olive oil, ¼ tsp salt, ¼ tsp smoked paprika, and a pinch of pepper on a lined baking sheet, then spread in a single layer.Roast for 20–25 minutes, flipping once halfway through, until fork-tender and lightly caramelized. Remove and reduce oven temperature to 375°F (190°C).
- In a large bowl, whisk together 8 eggs, ¼ cup milk, ¼ tsp smoked paprika, ¼ tsp salt, ¼ tsp black pepper, and red pepper flakes (if using) for about 60 seconds until frothy and pale yellow.Stir in two-thirds of the grated Gruyère, reserving the remaining third for topping.
- Heat 1 tbsp olive oil in a 10-inch oven-safe skillet over medium heat. Cook the sliced onion for 8–10 minutes until soft and golden, then add garlic and thyme and stir for 60 seconds until fragrant.Add the baby spinach and cook for 1–2 minutes, stirring, until wilted and any excess moisture has evaporated. Spread the mixture evenly across the pan.
- Scatter the roasted butternut squash evenly over the onion and spinach layer. Give the egg mixture a final stir, then pour it gently and evenly over the vegetables.Sprinkle the reserved Gruyère over the top.
- Cook the frittata on the stovetop over medium-low heat for 3–4 minutes without stirring, until the edges are just set and beginning to pull away from the sides. The center will still look liquid — this is correct.
- Transfer the skillet to the 375°F oven and bake for 12–15 minutes until the top is golden and puffed and the center reads 165–170°F on an instant-read thermometer.Remove from oven and let rest in the pan for 5 minutes before slicing.
- Scatter freshly chopped parsley or chives over the top, then slice into 6 wedges and serve warm, at room temperature, or chilled.
Notes
- Dry the vegetables first: Make sure all moisture from the spinach has cooked off before adding the eggs, or the frittata may turn out watery.
- Use room-temperature eggs: Cold eggs can cook unevenly. Let them sit out for 15 minutes before starting.
- Don't over-whisk: Whisk until frothy but not overly beaten — this keeps the frittata tender rather than tough.
- Grate cheese fresh: Pre-shredded cheese contains anti-caking agents that affect melting. A freshly grated block of Gruyère melts much more smoothly.
- Cheese substitutions: Feta adds a salty, tangy flavor; sharp cheddar gives a more robust, familiar taste; goat cheese adds creaminess. All work well.
- Frozen squash works: Thaw completely and pat very dry before roasting to prevent a soggy frittata. Begin checking for doneness around the 15-minute mark.
- Refrigerator storage: Cover and refrigerate for up to 4 days. Serve cold or reheat gently at 325°F for 8–10 minutes, or in the microwave in 30-second intervals on medium power.
- Freezer storage: Wrap individual slices tightly and freeze for up to 2 months. Thaw overnight in the fridge before reheating.
- Add-ins: Cooked bacon, pancetta, crumbled Italian sausage, or roasted red peppers all make excellent additions — stir them in with the squash layer.
- Make it dairy-free: Substitute unsweetened oat milk or almond milk for the whole milk, and use a plant-based cheese or omit entirely.
Nutrition
Serving: 1SliceCalories: 245kcalCarbohydrates: 10gProtein: 16gFat: 16gSaturated Fat: 6gPolyunsaturated Fat: 2gMonounsaturated Fat: 7gCholesterol: 255mgSodium: 320mgPotassium: 380mgFiber: 2gSugar: 3gVitamin A: 90IUVitamin C: 20mgCalcium: 25mgIron: 10mg
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