Sweet Potato Crispy Kale Frittata with Pine Nuts
Golden-crusted frittata combining caramelized onions, roasted sweet potato, and crispy kale in a creamy cheddar egg base. The deep savory layers from slow-cooked onions contrast with bright thyme-infused potato and toasted pine nuts for texture. Serve warm for brunch, lunch, or a light dinner. This version emphasizes technique--separate roasting and caramelizing components before combining--creating distinct flavors that don't muddy together. The cast iron finish crisps the kale while the center stays just-set for custardy bites.
Ingredients
- 2 medium sweet potatoes, peeled and cubed
- 5 ½ tablespoons olive oil, divided
- 6 sprigs fresh thyme, whole
- ½ teaspoon garlic powder
- ½ teaspoon salt
- ½ teaspoon pepper
- 1 large or 2 medium onions, sliced
- 1 cup curly kale
- 8 large eggs, room temperature
- ⅓ cup heavy cream
- ¾ cup grated mature cheddar cheese, divided
- 3 tablespoons toasted pine nuts
Instructions
- 1
Preheat oven to 375F.
- 2
Toss cubed sweet potatoes with 2 tablespoons olive oil, thyme sprigs, garlic powder, salt, and pepper. Roast for 45 minutes, stirring occasionally, until tender and golden.
- 3
Meanwhile, heat 2 tablespoons olive oil in heavy pan over low heat. Add sliced onions and caramelize slowly for 45 minutes, stirring occasionally, until deep golden brown.
- 4
Rub kale with 1 tablespoon olive oil and salt in medium bowl. Set aside.
- 5
When sweet potatoes finish, remove from oven and increase temperature to 400F.
- 6
Whisk eggs with cream in large bowl. Season with salt and pepper. Stir in three-quarters of cheddar.
- 7
Heat cast iron skillet over medium-low heat with 1/2 tablespoon olive oil. Pour egg mixture into pan. Add roasted sweet potatoes and caramelized onions.
- 8
Top with remaining cheddar and rubbed kale, pressing lightly into surface.
- 9
Cook stovetop 3 to 4 minutes until edges set.
- 10
Transfer skillet to oven for 10 minutes until center is just slightly wobbly and kale is crispy.
- 11
Cool 5 minutes. Top with toasted pine nuts before serving.
Tips
Start onions and sweet potatoes simultaneously--both need 45 minutes--to time components perfectly for assembly.
Room-temperature eggs incorporate smoother into cream without temperature shock; cold eggs can create grainy texture.
The slight wobble in center after oven cooking ensures residual heat finishes cooking without overcooking; it sets fully during 5-minute rest.
Good to Know
Cover and refrigerate up to 4 days. Reheat gently in 325F oven for 8-10 minutes or skillet over low heat.
Roast sweet potatoes and caramelize onions up to 2 days ahead. Store separately in airtight containers. Assemble and bake frittata fresh.
Slice into wedges while still warm. Serve with arugula salad, crusty bread, or roasted vegetables. Pairs with light white wine or herbal tea.
Common Mistakes
Overmix eggs to avoid tough, rubbery texture; whisk just until combined.
Don't skip the 5-minute rest; it allows carryover cooking and easier slicing.
Avoid high heat when caramelizing onions; low heat for 45 minutes builds deep flavor, not burnt edges.
Substitutions
Dairy-Free Swaps
General Alternatives
FAQ
Can I make this without a cast iron skillet?
Yes. Use an oven-safe nonstick or ceramic skillet. Cast iron provides superior heat distribution and crisping, but any oven-safe pan works. Reduce stovetop cooking slightly if using thinner metal.
What if the center is still too jiggly at 10 minutes?
Return to oven in 2-minute increments until just barely set in middle. Residual heat will continue cooking during 5-minute rest. Overcooked frittata becomes dry and tough.
Can I freeze leftover frittata?
Yes. Cool completely, wrap wedges individually in foil, and freeze up to 3 months. Thaw overnight in refrigerator. Reheat gently in oven to avoid rubbery eggs. Quality declines slightly after freezing.