Artichoke and Spinach Stuffed Shells

24 ounces spinach artichoke dip, at room temperature

1 cup ricotta cheese

1 egg

2 tablespoons fresh lemon juice

1 pinch crushed red pepper flakes, or to taste

salt and freshly ground pepper to taste

1 (16 ounce) package jumbo pasta shells

2 cups white sauce (such as bechamel)

1 cup shredded Gruyere cheese

½ cup grated Parmigiano-Reggiano cheese

Preheat the oven to 375 degrees F (190 degrees C).

Combine spinach artichoke dip and ricotta cheese in a bowl. Stir in egg, lemon juice, red pepper flakes, salt, and pepper; mix until well-combined. Set aside.

Bring white sauce to a simmer over medium-low heat. Stir in grated Gruyere cheese until cheese is melted and incorporated into sauce, 1 to 2 minutes. Set aside.

Fill a large pot with lightly salted water and bring to a boil. Stir in shells and return to a boil. Cook pasta uncovered, stirring occasionally, until cooked through, but still firm to the bite, about 11 minutes; drain. Set aside.

Pour half the white sauce mixture into the bottom of a 9x13-inch casserole dish; spread evenly.

Stuff pasta shells with the spinach artichoke mixture and place in casserole dish atop the white sauce, stuffed-side up.

Pour remaining white sauce over the tops of the shells and sprinkle with Parmigiano-Reggiano cheese.

Bake in the preheated oven until golden brown and bubbling, about 25 minutes.