Preheat the oven to 350°F (175°C) and generously grease a 12-cup standard muffin pan.

Heat a skillet over medium heat to cook and brown the Italian sausage, breaking it into fine crumbles until cooked through, then set aside; render the bacon until crispy, drain on paper towels, and chop finely.

Steam or light-sauté the broccoli florets, chopped kale leaves, and diced shallot until tender-crisp.

In a large bowl or liquid measuring pitcher, whisk the 12 large eggs vigorously with kosher salt and freshly ground black pepper until homogenous and well aerated.

Distribute the prepared solid ingredients into the muffin cups to establish the three flavor profiles: combine broccoli, chopped bacon, cheddar, and sliced chives in four cups; combine Italian sausage, diced shallot, chopped kale, and grated parmesan in four cups; combine baby spinach, halved grape tomatoes, thinly sliced green onion, and crumbled goat cheese in the remaining four cups.

Pour the whisked egg mixture evenly over the toppings in each cup, filling each cavity approximately three-quarters full.

Bake for 20 to 25 minutes, or until the egg muffins are fully set in the center and lightly golden on top.

Remove the muffin pan from the oven and allow the egg cups to rest for 5 minutes before running a butter knife around the edges to release them.