Step 1
In a large (12-inch) skillet over medium-high heat, melt the butter. Add the onion, season lightly with salt, and cook, stirring occasionally, until softened and translucent, about 5 minutes. Add the celery and garlic and stir until softened and fragrant, adjusting the heat as necessary to avoid scorching, about 2 minutes. Scrape the mixture into a 6- to 8-quart slow cooker.
Step 2
Add the chicken thighs, stock, wine and lemon juice to the slow cooker. Season with the red-pepper flakes, 1 teaspoon salt and a generous amount of black pepper; mix well to combine. Cover and cook on low for 4 hours. At this point, the dish can hold on the warm setting for several hours.
Step 3
About 20 minutes before you are ready to eat, add the frozen spinach and the artichoke hearts to the slow cooker. Cook on low until the spinach is hot and can be stirred into the stew. (For spinach that comes frozen in a block, this can take 15 to 20 minutes; frozen cut spinach in a bag takes less time to defrost and cook.)
Step 4
Add the cream cheese and dill, and stir until the cream cheese melts.
Step 5
Using the back of a spoon, press the chicken against the side of the pot to break it up into pieces. Taste and add more salt and black pepper, if necessary. Divide the stew among bowls and top with scallions and Parmesan.
