Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper. Place English muffin halves cut-side up on the sheet. Brush the cut sides lightly with melted butter. Bake for 5-7 minutes until lightly toasted and crisp around the edges.

While muffins toast, cook sausage in a skillet over medium heat, breaking it into small crumbles, until browned and cooked through, about 5-7 minutes. Transfer to a plate. In the same skillet (drain excess fat if desired), pour in beaten eggs. Cook over medium-low heat, gently stirring, until softly set but still slightly wet, about 2-3 minutes. Remove from heat.

Remove toasted muffins from oven. Sprinkle each half with a pinch of garlic powder and onion powder. Divide the scrambled eggs evenly among the 8 halves, spreading gently. Top with cooked sausage crumbles and diced ham. Sprinkle with cheddar and mozzarella cheeses.

Return the baking sheet to the oven. Bake for 8-10 minutes, or until the cheese is fully melted, bubbly, and starting to turn golden in spots.

Remove from oven. Immediately sprinkle with chopped chives, parsley, black pepper, and a pinch of red pepper flakes if using. Let cool for 2 minutes before serving.