1 bunch (14 leaves) collard greens, washed and ribs removed
4 tablespoons (1/2 stick) unsalted butter
3 tablespoons diced yellow onions
2 cloves garlic, minced
1/4 cup all-purpose flour
1/4 cup reduced-sodium chicken broth
2 cups half-and-half
1/2 cup (2 ounces) shredded Parmesan cheese
1/2 tablespoon fresh lemon juice
3/8 teaspoon salt
1/8 teaspoon cayenne pepper
3 tablespoons sour cream
1 jar (6 ounces) marinated artichoke hearts, drained and chopped
1/4 cup shredded whole-milk mozzarella cheese or 1 ounce mozzarella, cut into 4 slices
 crostini or pita chips

Bring a large pot of salted water to a boil over high heat. Add the collard greens and cook for 2 minutes to blanch, Drain the leaves and pat dry with paper towels. Stack the leaves and roll into a cigar. Cut the cigar in half lengthwise and thinly slice crosswise into long stripes.

Preheat the oven to 350 degrees.

Melt the butter in a medium saucepan over low heat. Add the onion and cook until softened, about 34 minutes. Add the garlic and cook until fragrant, about 2 minutes. Sprinkle with the flour and cook for 1 minute. Whisk in the broth and half-and-half, increase the heat to medium and cook, stirring occasionally, for 5 minutes. Reduce the heat to low. Add the Parmesan, lemon juice, salt, and cayenne. Stir until the cheese has melted.

Pour the cheese mixture into a food processor and add the slivered greens. Blend to pulse until the greens are in small pieces. Return the mixture to the saucepan and cook for 5 minutes to heat through.
Remove from the heat and stir in the sour cream and artichokes.

Pour the mixture into an 8 x 8-inch glass baking dish. Top with the mozzarella. Bake until the cheese is melted, about 10 minutes. Serve with crostini or pita chips.