For the Custardy Egg Base:

• 6 Large Eggs: Eggs are the absolute foundation of a frittata, providing structure, richness, and that signature custardy texture.

  • Large Eggs (Standard Size): This recipe is formulated for large eggs, which are the standard size in most grocery stores. If using medium or extra-large eggs, you may need to adjust the quantity slightly to maintain the correct ratio of eggs to other ingredients.
  • Fresh, High-Quality Eggs: Opt for fresh, high-quality eggs whenever possible. Fresher eggs will have firmer whites and yolks, contributing to a better texture and overall quality in your frittata.
  • Organic or Free-Range (Optional): If you prioritize ethical sourcing and potentially richer flavor, consider using organic or free-range eggs.
  • Egg Substitutes (Vegan Frittata Adaptations): For a vegan or egg-free frittata, explore egg substitutes like silken tofu (blended until smooth), chickpea flour batter (besan flour), or commercially available vegan egg replacers. These substitutes will require recipe adjustments and may result in a slightly different texture.

• ¼ cup Milk or Cream (Whole Milk or Heavy Cream Recommended): Milk or cream adds moisture, richness, and a smoother, more luxurious texture to the egg base, contributing to the frittata’s custardy consistency.

  • Whole Milk (Balanced Richness): Whole milk provides a good balance of richness and moisture, creating a delicious and satisfying frittata without being overly heavy.
  • Heavy Cream (Ultra-Rich and Decadent): Heavy cream will result in an ultra-rich, decadent, and incredibly creamy frittata. Use heavy cream for special occasions or when you desire maximum indulgence.
  • 2% Milk or Skim Milk (Lighter Options): You can use 2% milk or skim milk to reduce the fat content and calories. However, the frittata will be slightly less rich and creamy compared to using whole milk or heavy cream.
  • Non-Dairy Milk Alternatives (Vegan/Dairy-Free Options): For a vegan or dairy-free Cast Iron Frittata, use unsweetened non-dairy milk alternatives like almond milk, soy milk, oat milk, or coconut milk (from a carton, not canned). Oat milk and soy milk tend to provide a creamier texture compared to almond milk.

• Salt and Black Pepper (to taste): Salt and black pepper are fundamental seasonings, essential for enhancing the flavors of all the other ingredients and ensuring the frittata is well-seasoned and delicious.

  • Kosher Salt or Sea Salt (Recommended): Kosher salt or sea salt are preferred for their clean, pure flavor and consistent grain size.
  • Freshly Ground Black Pepper (Superior Aroma): Freshly ground black pepper is always superior in aroma and flavor to pre-ground pepper.
  • Season Generously: Don’t be shy with seasoning! Eggs can be bland on their own, so generous seasoning with salt and pepper is crucial for a flavorful frittata. Taste the egg mixture before baking and adjust seasoning as needed.

For the Flavorful and Customizable Filling:

• 1 tablespoon Olive Oil or Butter: Olive oil or butter is used to sauté the vegetables and aromatics, adding flavor and preventing sticking in the cast iron skillet.

  • Olive Oil (Savory and Healthy): Olive oil adds a savory flavor and healthy monounsaturated fats. Extra virgin olive oil is preferred for its richer flavor.
  • Butter (Rich and Buttery): Butter, whether dairy or vegan, adds a rich, buttery flavor and helps vegetables caramelize beautifully.
  • Combination (Best of Both Worlds): Using a combination of olive oil and butter can provide the health benefits of olive oil and the flavor richness of butter.

• ½ cup Chopped Onion (Yellow, White, or Red): Onion forms an aromatic base for the filling, adding savory depth and sweetness as it cooks.

  • Yellow Onion (Versatile and Mildly Sweet): Yellow onion is a versatile and commonly used choice, providing a balanced flavor that complements many fillings.
  • White Onion (Sharper and More Pungent): White onion offers a sharper and more pungent flavor, which can be desirable for bolder frittata fillings.
  • Red Onion (Sweeter and Milder, Adds Color): Red onion provides a sweeter and milder flavor and adds a beautiful reddish-purple color to the filling.
  • Shallots (More Delicate and Subtle): For a more delicate and subtle onion flavor, you can use shallots instead of onions.

• 1 cup Chopped Vegetables (Choose Your Favorites): The beauty of a frittata lies in its versatility. You can use virtually any combination of vegetables to create your desired flavor profile and utilize seasonal produce or leftovers. Here are some excellent vegetable options:

  • Leafy Greens: Spinach, kale, arugula, chard (add towards the end of sautéing as they wilt quickly).
  • Mushrooms: Sliced cremini, button, shiitake, or oyster mushrooms (sauté until tender and browned).
  • Bell Peppers: Diced red, green, yellow, or orange bell peppers (add sweetness and crunch).
  • Asparagus: Chopped asparagus spears (add during the last few minutes of sautéing to maintain some crispness).
  • Broccoli or Cauliflower: Small florets of broccoli or cauliflower (lightly steam or blanch before sautéing to ensure they cook through in the frittata).
  • Zucchini or Summer Squash: Diced zucchini or summer squash (sauté until tender, may need to squeeze out excess moisture).
  • Tomatoes: Cherry tomatoes (halved), sun-dried tomatoes (oil-packed, drained), or roasted tomatoes (add sweetness and acidity).
  • Roasted Vegetables (Pre-Cooked): Roasted vegetables like potatoes, sweet potatoes, butternut squash, or Brussels sprouts (add pre-cooked roasted vegetables directly to the frittata for convenience).

• ½ cup Cooked Protein (Optional, Choose Your Favorite): Adding cooked protein transforms the frittata into a more substantial and satisfying meal. Choose from a variety of cooked protein options:

  • Cooked Sausage or Bacon: Crumbled cooked breakfast sausage, Italian sausage, chorizo, or bacon (adds savory, meaty flavor and richness).
  • Cooked Ham or Prosciutto: Diced cooked ham or prosciutto (adds salty, savory flavor and texture).
  • Shredded Cooked Chicken or Turkey: Shredded rotisserie chicken, leftover roasted chicken or turkey (lean protein option).
  • Smoked Salmon or Lox: Flaked smoked salmon or lox (adds rich, smoky, and salty flavor).
  • Cooked Shrimp or Crabmeat: Cooked shrimp or crabmeat (delicate seafood option).
  • Canned Tuna or Salmon: Canned tuna or salmon (drained, budget-friendly protein option).
  • Cooked Legumes (Vegetarian/Vegan Protein): Cooked chickpeas, lentils, or black beans (plant-based protein option, add heartiness and fiber).

• ½ cup Shredded Cheese (Choose Your Favorites): Cheese adds richness, flavor, and melty goodness to the frittata. Select cheeses that complement your chosen vegetables and proteins. Here are some excellent cheese options:

  • Cheddar Cheese: Sharp, medium, or mild cheddar (classic cheesy flavor).
  • Monterey Jack or Pepper Jack Cheese: Mild and melty Monterey Jack, or spicy Pepper Jack (adds a kick).
  • Gruyere or Swiss Cheese: Nutty and slightly sweet Gruyere or Swiss (adds sophisticated flavor).
  • Mozzarella or Provolone Cheese: Mild and melty mozzarella or provolone (adds creamy, stretchy texture).
  • Feta Cheese: Crumbled feta cheese (adds salty, tangy, and briny flavor).
  • Goat Cheese: Crumbled goat cheese (adds tangy, creamy, and slightly earthy flavor).
  • Parmesan Cheese: Grated Parmesan cheese (adds salty, umami, and nutty flavor, can be added to the egg mixture and sprinkled on top).
  • Vegan Cheese Shreds (Vegan/Dairy-Free Option): Vegan cheddar shreds, mozzarella shreds, or other vegan cheese alternatives (ensure they melt well).

• Optional – Fresh Herbs (Chopped): Fresh herbs, added at the end, brighten the flavors and add aromatic complexity to the frittata. Choose herbs that complement your filling ingredients. Excellent options include:

  • Chives: Mild onion flavor and delicate freshness.
  • Parsley: Fresh, clean, and slightly peppery flavor.
  • Basil: Sweet, slightly peppery, and aromatic (pairs well with Mediterranean-inspired fillings).
  • Dill: Fresh, herbaceous, and slightly tangy (pairs well with seafood or asparagus).
  • Thyme: Earthy, slightly lemony, and aromatic (pairs well with mushrooms or roasted vegetables).
  • Rosemary: Piney, resinous, and aromatic (use sparingly, pairs well with hearty fillings).