Preheat your oven to 350°F. While it heats, halve the bell peppers lengthwise and remove all seeds and membranes to create clean shells—I like to trim a thin slice from the bottom of each pepper half so they sit flat and stable in the baking dish. Brown the turkey sausage in a skillet over medium-high heat, breaking it into small crumbles as it cooks, about 5-7 minutes until fully cooked through. Set the cooked sausage aside on a plate.

In the same skillet, heat 1.5 tsp avocado oil over medium-high heat. Dice the mushrooms into small pieces and add them to the hot oil with a pinch of salt. Sauté for about 5 minutes, stirring occasionally, until the mushrooms are golden and have released their moisture. This step builds deeper flavor through browning—rushing it will leave them watery and bland. Transfer the cooked mushrooms to a bowl and let cool slightly.

In a large mixing bowl, whisk together the 4 eggs and 1/2 cup egg whites until well combined and slightly frothy. Add the cooked sausage from Step 1 and the sautéed mushrooms from Step 2, then fold in the spinach. Season with 3/4 tsp salt, 1/4 tsp black pepper, and 1/4 tsp garlic powder, stirring until evenly distributed. The mixture should be loose and pourable—this allows it to cook evenly throughout the peppers.

Pour 2 tablespoons of water into the bottom of a 9x13 inch baking dish (or similar size that fits your peppers snugly). Place the prepared pepper halves cut-side up in the dish. Divide the egg mixture evenly among the pepper shells, filling each one to just below the rim—avoid overfilling, as the eggs will puff slightly as they cook. Top each filled pepper with about 1 tablespoon of cheddar cheese, distributing it evenly across all six halves.

Cover the baking dish tightly with aluminum foil and place it in the preheated 350°F oven. Bake for 25 minutes covered—the foil traps steam and helps the eggs cook through gently without the cheese browning too quickly. After 25 minutes, carefully remove the foil. I like to tent the foil slightly before removing it to avoid steam burns. Continue baking uncovered for another 20-25 minutes, until the egg filling is set in the center (a knife inserted should come out clean) and the cheese is melted and lightly golden.

Remove the stuffed peppers from the oven and let them rest for 5 minutes before serving. This brief rest allows the eggs to firm up slightly and makes them easier to handle, plus it lets the residual heat finish cooking any remaining undercooked spots in the center. Serve warm directly from the baking dish, or transfer to individual plates.