Crack 6 eggs into a cold nonstick pan and add 3 tbsp cold unsalted butter cubes (no preheating, no salt).
Place pan over medium heat and stir constantly, breaking yolks and scraping sides for ~40 seconds.
Remove pan from heat and keep stirring for 30 seconds; repeat short on-off heat cycles for 2–3 minutes until creamy.
Remove from heat when eggs are ~90% done, stir in crème fraîche/Greek yogurt/sour cream or more cold butter, then season with salt, pepper, and optional garnishes.
Serve immediately over toasted sourdough or brioche, with optional toppings like avocado, tomatoes, or smoked salmon.