Friday is the perfect day for a frittata. The week's cooking is winding down, the fridge holds a motley collection of cooked potatoes, wilting greens and odds and ends of cheese. Instead of binning them, you can turn them into a golden, satisfying meal that costs very little and tastes far better than the sum of its parts. A frittata is forgiving, adaptable and quick enough for a weeknight. Here is how to make one that works every time.

Why a Friday Frittata Saves Money and Waste

British households throw away a shocking amount of food, and cooked potatoes and greens are among the worst offenders. A frittata flips that around. Eggs are the binder, not the main event, so a little cheese, a few spuds and a handful of tired spinach become a substantial dinner. You also use one pan and the oven, which keeps energy use down. Unlike a fiddly French omelette, a frittata is finished in the oven, so you can get on with other things while it cooks. It is the ultimate fridge-foraging meal.

The Core Formula: Eggs, Dairy, Starch, Veg, Cheese

For a 23cm ovenproof frying pan, this ratio works reliably:

• 6–8 large eggs — the binder. More eggs make a firmer set.
• 100ml milk or single cream — for a softer curd. Water works in a pinch.
• 300g cooked starch — potatoes, pasta, even leftover rice or bread cubes.
• 200–300g vegetables — cooked or raw, but squeeze out excess water.
• 100g cheese — grated Cheddar, crumbled feta or Stilton, or a mix of odds.
• 1 tablespoon fat — olive oil, butter or dripping for the pan.

Season boldly with salt, black pepper and nutmeg. Nutmeg is the secret to a frittata that tastes properly savoury.

What to Do with Cooked Potatoes and Greens

Leftover roast potatoes are ideal: chop them into 2cm chunks and let them crisp in the pan before you add the eggs. Boiled new potatoes work too, as does the flesh of a baked potato. Avoid mash unless you want a softer, more pudding-like texture — it can make the frittata dense. For greens, cabbage, kale, spinach, chard, sprouts and broccoli all work. If they are already cooked, squeeze them in a clean tea towel to remove excess water, otherwise the frittata will weep. Raw greens like spinach can be wilted in the pan first. Add any leftover cooked onion, leek or garlic for depth.

Step-by-Step: From Fridge to Oven

Preheat the oven to 180°C fan (200°C conventional, gas mark 6). Heat the fat in your ovenproof frying pan over a medium heat. Add any raw alliums — onion, leek, spring onion — and cook until soft. Add firmer vegetables and your cooked potatoes. Fry for 3–4 minutes until everything is hot and lightly coloured. Season well.

In a bowl, whisk the eggs with the milk, a good pinch of salt, pepper and nutmeg. Pour over the pan contents. Cook on the hob for 2–3 minutes, until the edges are set and the middle is still wobbly. Transfer to the oven for 15–20 minutes, until puffed, set and golden. If the top needs more colour, finish under a hot grill for 2 minutes. Rest for 5 minutes, then loosen with a spatula and slide onto a board. Cut into wedges.

Variations for Any Season

Spring: asparagus, peas, wild garlic and goat's cheese. Summer: courgette, tomato, basil and feta. Autumn: roasted squash, mushrooms, sage and blue cheese. Winter: leeks, kale, root vegetables and a sharp Cheddar. You can also go Spanish with just potato, onion and a little paprika, or Italian by folding in leftover cooked pasta and a spoonful of pesto. The formula stays the same; only the leftovers change.

Serving and Storing Your Frittata

Serve warm or at room temperature. A sharp green salad, a spoonful of chutney and some crusty bread turn it into a proper Friday feast. Leftovers keep in the fridge for up to three days. Eat cold in sandwiches or wraps, or reheat in a 160°C oven for 10 minutes. You can also freeze slices wrapped in baking parchment for up to a month; thaw overnight in the fridge before reheating. So next Friday, before you reach for the bin, reach for the eggs. Your wallet and your conscience will thank you.