Preheat your oven to 350°F (175°C).
To make the bacon crumbles: In a skillet over medium heat, cook the bacon slices until they are crispy. Remove the bacon and place it on a paper towel-lined plate to drain excess grease. Once cooled, crumble the bacon into small pieces.
In the same skillet over medium heat, using a teaspoon of the bacon grease or some cooking oil, sauté the garlic, onions, spinach, and diced green and red bell peppers and onions until they become soft and tender, about 4-5 minutes. Season with a pinch of salt and pepper. Stir, then set aside.
In a large mixing bowl, crack the 8 eggs and whisk them together. Add in crumbled bacon, sautéed and vegetable mix. Then, stir in as much Sriracha sauce as you like. Mix everything well to combine. Adjust the Sriracha to your preferred level of spiciness.
In a large bowl, whisk all 8 eggs, then stir in the veggie mixture along with the bacon crumbles. Add in any amount of Sriracha desired. I like things a bit spicier so I used 2-3 tablespoons (or a really generous squeeze).
Pour the egg mixture evenly into a greased cupcake pan or muffin pan. Fill each slot nearly to the top. We used a cupcake pan for smaller bite-sized egg muffin cups.
Bake for 15-18 minutes in the preheated oven, or until a toothpick comes out clean or until the breakfast muffins are set in the middle and the tops are slightly golden.