Step 1

Preheat the oven to 400°. Bring a large pot of salted water to a boil. Add the ravioli and cook according to the package directions. Drain the ravioli.

Step 2

Combine the spinach and ravioli in a 9-by-13-inch baking dish and gently toss to combine.

Step 3

Melt the butter in a medium saucepan over medium-low heat. Whisk in the flour and cook, whisking constantly, until golden, 2 to 3 minutes (don't let the flour burn). Slowly whisk in the half-and-half until smooth. Cook, whisking occasionally, until thickened, about 7 minutes.

Step 4

Reduce the heat to low. Whisk in the pesto until just heated through, about 1 minute.

Step 5

Pour the pesto cream sauce over the spinach and ravioli. Spread with a spoon, making sure all the ravioli are coated. Sprinkle with the mozzarella and parmesan. Bake until the sauce is bubbling and the edges are browned, about 25 minutes. Let cool 5 minutes before serving.