Preheat the oven to 425°F then line two cookie sheets with parchment paper. Wash the spaghetti squash and slice off the stem at the top (if it is too hard to cut, pierce it a few times then microwave it for about 5 minutes to help soften it). Cut each squash in half lengthwise then use a spoon to scrap out the seeds and the darker yellow strands that the seeds are attached to. Rub a little bit of high heat oil on the inner rim of the squash then place each half face down on the baking sheet. Roast in the oven for 30-45 minutes, depending on the size (longer for larger squash). You can test to see if it’s done by squeezing the outside with an oven mitt. If it’s easily pliable then it’s ready. Remove it from the oven and set aside to cool.While the squash is roasting, prepare the pesto by combining the spinach, garlic, pecans, olive oil, lemon zest/juice, and salt & pepper in a blender or a food processor. Blend on high for about 10 seconds, scrape down the sides, then blend for another 20 seconds, until smooth.Once the squash has cooled down (for at least 15 minutes), use a fork to scrape the insides. Distribute the pesto and the artichoke hearts into each half then top with shredded cheese. Turn the oven to broil then transfer the squash back to the oven and cook until the cheese is golden and bubby, for about 5 minutes. Serve warm and enjoy!