Preheat the oven to 375 degrees F.

Butter the insides of the English muffins. Place the English muffins on a large baking sheet, buttered side up. Top each bottom half with 1 slice of cheese. Bake until the cheese melts, about 2 to 3 minutes. Remove from oven and set aside.

Crack the eggs into a medium bowl and whisk until combined.

In a large nonstick skillet, heat the butter or olive oil over medium heat. Carefully pour the eggs into the hot pan and season with salt and pepper. Don’t stir, let the eggs cook for 20 to 30 seconds so they can set up a little.

Turn the heat to low. With a heat-resistant rubber spatula, gently push one edge of the egg into the center while tilting the pan to allow the still liquid egg to flow in underneath.

Continue cooking, folding and stirring the eggs every few seconds, making sure you scrape the spatula along the bottom and sides of the pan.

Remove the pan from the heat when the eggs are mostly set, but still soft with a little liquid left. Season with salt and pepper, to taste.

Assemble the sandwiches while the eggs are hot. Divide the scrambled eggs between the English muffin bottoms and top with bacon and mashed avocado. Garnish with chives, if desired. Close the sandwiches with the other English muffin halves and serve immediately.