Step 1

Place chicken breasts in a large pot and cover with water. Bring to a boil; cook chicken until an instant-read thermometer inserted into the center reads at least 165 degrees F (74 degrees C), about 15 minutes. Drain and cool until easily handled, about 5 minutes; slice into smaller pieces.

Step 2

Preheat oven to 350 degrees F (175 degrees C).

Step 3

Bring a large pot of lightly salted water to a boil; add penne and cook, stirring occasionally, until tender yet firm to the bite, about 9 minutes. Drain.

Step 4

Mix chicken slices, penne, Alfredo sauce, artichoke hearts, spinach, and diced tomatoes together in a 9x13-inch baking dish. Season with salt and pepper.

Step 5

Bake in the preheated oven until sauce is bubbly, about 30 minutes.