In a large skillet, heat the olive over over medium-high heat. Add the shallot, asparagus pieces, artichoke hearts, spinach, garlic, and frozen peas. Cook until vegetables are tender and spinach is wilted, about 5 minutes. Pour the vegetables into a large bowl and set aside while you cook the pasta and sauce.
Bring a large pot of water to a boil and salt generously. Cook pasta according to package instructions.
While the pasta is cooking, make the creamy lemon sauce. Place the large skillet you used to cook the vegetables back on the stove and melt the butter. Whisk in the flour, whisking until you don't have any clumps. Slowly whisk in the almond milk, about 1/2 cup at a time, whisking vigorously. Add the lemon zest and keep whisking until the sauce comes to a boil. Reduce heat to low and whisk occasionally until the sauce thickens. Add in the lemon juice and sliced lemons. Season the sauce with salt and black pepper, to taste.
Drain the pasta and add it to the thickened lemon sauce. Stir in the cooked vegetables and stir until the pasta and vegetables are well coated with the creamy lemon sauce. Remove the lemon slices with tongs or a spoon.
Garnish with fresh basil and parmesan cheese, vegan parmesan cheese, or nutritional yeast, if using. Serve warm.