Begin by melting 2 tablespoons of butter in a skillet over medium heat. Add thinly sliced onions and stir occasionally for 15-20 minutes until golden brown.

In a bowl, crack 4 large eggs and whisk with 2 tablespoons of heavy cream, salt, and pepper. In a non-stick pan, cook the mixture over low heat for about 5-7 minutes.

Toast brioche buns cut-side down in a separate pan over medium heat for 2-3 minutes until golden brown.

Assemble the sandwich by placing scrambled eggs on the bun, adding caramelized onions, and a sprinkle of cheese. Optionally add fresh herbs or avocado.

Slice in half and serve immediately while warm.