Heat the fat: place a skillet over medium heat and add 1 tablespoon olive oil or butter. Let it warm until the fat shimmers (or butter melts and foams) so the mushrooms start to brown when they hit the pan.

Sauté the mushrooms: add the sliced mushrooms in a single layer if possible and cook, stirring occasionally, until they are tender and release some of their juices. Look for light browning and a glossy finish.

Wilt the spinach: add the fresh spinach to the skillet and stir it into the warm mushrooms until it’s just wilted and bright green. There should not be excess liquid pooling in the pan.

Whisk the eggs: crack the 4 eggs into a bowl and whisk with a pinch of salt and a few grinds of pepper until fully combined and slightly frothy.

Combine and cook gently: pour the whisked eggs into the same skillet with the mushrooms and spinach. Lower the heat slightly if the pan is very hot.

Stir to curd: using a spatula, stir gently and continuously to form medium-sized curds. Scrape the bottom and edges for even cooking.

Serve hot: remove the skillet from heat as soon as the eggs are cooked through. Taste and adjust salt and pepper, then serve immediately.