Heat a large (12-inch) cast iron or non-stick skillet to medium-high heat. Place the bacon on the hot skillet and cook 2 to 3 minutes. Flip and continue cooking until bacon is golden-brown and crispy, about another 1 to 2 minutes. Transfer the bacon to a cutting board. Allow it to cool, then chop and set aside.

Add the diced onion to the hot skillet with the bacon drippings. Cook, stirring occasionally, until onion begins to brown, about 5 to 8 minutes. Note: if onion begins sticking to the pan at any point, add 1 tablespoon olive oil to the skillet.

Add butternut squash, apple, cinnamon, oregano, thyme, red pepper flakes, and sea salt. Stir well and cover. Cook, stirring occasionally, until butternut squash reaches desired doneness, about 10 to 15 minutes.

Remove lid, add the spinach, and re-place the lid. Cook until spinach has wilted, about 1 to 2 minutes.

Add the pure maple syrup and stir well. Taste hash for flavor and add more sea salt to taste.

Serve butternut squash hash with sunny side up, fried, poached, or scrambled eggs (for AIP, omit eggs).