First, you want to make tofu cream sauce. Drain the tofu and then squeeze as much liquid out of the tofu as you can over the sink.(You don't need to save any liquid, just let it go down the drain) I just like to use my hands to squeeze it, it is fine if it starts to break apart. You are going to blend it. 
Break the tofu into chunks, and add the tofu to a blender.
Then add the non-dairy milk, nutritional yeast, lemon juice, red pepper flakes and a pinch of salt and pepper to the blender. Blend on high, scraping down the sides of the blender as needed until the mixture is completely smooth. This may take a few minutes, depending on your blender.
Set aside the tofu cream sauce.
Now, in a large soup pot, heat the olive oil on medium high. Then add the onion and garlic. Reduce heat to medium low and sauté for 4-5 minutes or until the onion is translucent. 
Next, squeeze all of the liquid out of the thawed spinach and add it to the pot. Then add the chopped artichoke hearts. Season with a pinch of salt and pepper and and stir to combine. 
Continue to sauté for another 2-3 minutes. 
Then, pour the vegetable broth into the pot. Stir to combine.
Next, pour the tofu cream sauce you made into the pot and whisk to combine the cream sauce and the broth. If it looks like it isn't blending, just continue whisking until it is fully combined. Season with a few pinches of salt and pepper.
Bring to a simmer, don't bring it to a rolling boil, it will get really frothy. Reduce heat to low, and continue to simmer for 5-10 minutes. 
Taste and adjust seasoning. I always add more salt and pepper, and sometimes extra lemon juice. 
I like to serve with bread that I tossed in olive oil and Italian seasoning and bake at 400 degrees(F) for 10 minutes or until brown and crunchy. 
Serve immediately .