Prepare linguini pasta as directed on the package. Drain and set aside.
In a saucepan over medium-high heat, melt the butter. Add sliced garlic and sliced mushrooms. Sautee until mushrooms are nice and brown at the edges. Add the garlic powder and stir, cooking for another 30 seconds.
Add the chicken stock to the pan and stir. Add the lemon juice into the pan. Sprinkle the flour on top, stirring quickly so they don't form clumps.
When chicken stock is starting to bubble and boil, add the shredded leftover rotisserie chicken and chopped artichoke hearts to the pan. Stir and cook for another 1-2 minutes. Next, add the chopped sun-dried tomato pieces. Season with salt and pepper to taste.
Once the sauce has thickened to your desired level of thickness (I prefer mine to be thick and gravy-like), remove from heat.
Ladle the sauce over your cooked pasta. Sprinkle cheese on top, if desired.