Rinse the spinach and brush the mushrooms clean. Slice the mushrooms and whisk the three eggs with a pinch of salt and pepper.
Heat the butter in a skillet over medium-high heat. Sauté the mushrooms for a couple of minutes until golden, then add the spinach. Stir until the spinach is wilted.
Pour the whisked eggs over the vegetables. Gently stir with a spatula until the eggs are just set but still creamy. Crumble the goat cheese over and let it warm through for about half a minute.
Transfer the scrambled eggs to a plate and serve immediately, with freshly ground pepper on top.