Preheat and prep pan: Preheat the oven to 350°F and coat a 12-cup muffin tin with cooking spray, making sure to cover the corners so the muffins release easily after baking.

Cook the turkey bacon: In a skillet over medium heat, cook the chopped turkey bacon until crisp and browned, about 5 minutes, then transfer to a paper towel-lined plate.

Sauté the vegetables: In the same skillet, cook the diced bell pepper until softened, about 3 minutes, then add the spinach and stir until wilted, about 1 minute more.

Whisk the eggs: In a large bowl, whisk the eggs until the color turns pale yellow and the surface looks slightly foamy, which takes about 1 minute of steady whisking.

Add cottage cheese and seasoning: Stir the cottage cheese, salt, black pepper, and garlic powder into the whisked eggs until the mixture looks smooth and evenly combined.

Combine the fillings: Fold the cooked turkey bacon, sautéed vegetables, half of the shredded cheddar, and the sliced green onions into the egg mixture so each scoop has a little of everything.

Fill the muffin cups: Divide the egg mixture evenly among the 12 prepared muffin cups, filling each about three-quarters full to leave room for rising.

Top with remaining cheese: Sprinkle the remaining shredded cheddar cheese evenly over the tops of the filled muffin cups.

Bake until set: Bake for 18 to 22 minutes, until the tops turn golden and the centers spring back when gently pressed instead of jiggling.

Cool in the pan: Let the muffins rest in the tin for 5 minutes, then run a knife around the edges to loosen before lifting them onto a wire rack to finish cooling.