In a bowl, whisk together eggs, heavy cream, garlic powder, salt, and pepper until well combined.
Melt 1 tablespoon butter in a large non-stick skillet over medium-high heat and add sliced mushrooms.
Cook mushrooms for 5-6 minutes without stirring too much, until golden brown and any liquid has evaporated.
Add spinach to the skillet and cook for 1 minute until wilted, then push vegetables to one side.
Add remaining butter to the empty side of the pan, pour in the egg mixture, and gently scramble for 2-3 minutes until soft curds form.
Fold the vegetables into the eggs and serve immediately while hot and creamy.