Place a rack in the center of your oven and preheat the oven to 400 degrees F. Roast the spaghetti squash according to this recipe for Roasted Spaghetti Squash. When the squash has finished cooking, fluff the squash strands to make “noodles.”
Measure and set out the frozen peas (they don’t need to completely thaw; just let them warm up at room temp while you make the rest of the recipe).
While the squash roasts, place the bacon pieces in a large, deep skillet or Dutch oven. Cook over medium, until the bacon is crisp and the fat has rendered, about 8 to 10 minutes. Don’t rush it—crispy bacon takes patience and you don’t want it to burn. With a slotted spoon, scoop the bacon onto a paper towel-lined plate and blot away any extra grease. Discard all but 1 tablespoon drippings from the pan.
While the bacon cooks, in a medium bowl, whisk together the eggs and Parmesan.
Return the pan to the stove and turn the heat to low. Add the squash noodles to the pan and sprinkle with the garlic. Cook for 1 minute, just long enough to coat the noodles with the bacon drippings and to allow the garlic to become fragrant.
If your squash is super hot for any reason, let it cool for a few minutes before proceeding; you want it warm enough to cook the eggs, but not so hot the scramble. Add the egg/Parm mixture to the noodles. Stir constantly with a wooden spoon, so that you evenly coat the squash with the eggs and Parmesan. The mixture will be very liquidy at first, but just keep stirring. You want the eggs to slowly cook.
After about 8 minutes, you'll notice the mixture has thickened and is looking creamy, but there will be some liquid in the pan—this is moisture being released by the noodles. At this point, increase the heat to medium low and continue cooking until most of the liquid evaporates. 100% won't cook off—this is a fact of life when cooking with spaghetti squash—but the mixture should continue to thicken somewhat and look nice and creamy.
Turn off the heat and stir in the salt, pepper, bacon, and peas. Taste and adjust seasoning as desired. Enjoy immediately, sprinkled with additional Parmesan and an extra pinch of black pepper.
Notes
TO STORE: Refrigerate carbonara in an airtight storage container for up to 4 days.
TO REHEAT: Gently rewarm leftovers in a large skillet on the stovetop over medium-low heat.