Bring a large pot of water to a boil. Once water is boiling, add pasta and cook until al dente, about 7-10 minutes depending on the type of pasta. Drain, reserving ½ cup of pasta cooking water, and set aside.
Meanwhile, in a large saucepan or skillet, melt butter over medium-high heat. Add onions and mushrooms and sauté until veggies are tender, about 7 minutes. Add in flour and garlic, and stir constantly for about 1 minute.
Slowly whisk in milk. Make sure the flour is completely incorporated.
Stirring constantly, bring the milk mixture to a boil. Slowly boil while stirring for about 2 minutes or until the mixture thickens. Stir in cream cheese until it is incorporated.
Reduce heat to medium, and stir in salt & artichokes. Cook for about 2 minutes, stirring often.
Remove from heat and stir in Parmesan and blue cheese. Stir in lemon juice.
Add the cooked & drained pasta to the cheese-vegetable mixture. Stir together gently until all the pasta is coated. If needed, add a few tablespoons of reserved pasta cooking water to thin sauce.
Sprinkle with parsley and serve with lemon wedges if desired.