Ina Garten has always believed that store-bought is fine — most of the time. Mike Smith/NBCU Photo Bank/NBCUniversal via Getty Images via Getty Images

While testing recipes for her newest cookbook, Ina Garten wanted to prove her most famous claim: Sometimes, store-bought really is fine!

"Truly delicious dishes don't require hours of hands-on time in the kitchen," Garten wrote in "Simply Ina," which was released on Tuesday. "They just need a little thought and a few good ingredients."

Garten has a whole list of store-bought ingredients that she trusts , and they feature prominently in the new cookbook. The "Barefoot Contessa" star said she even tested every brand of mashed potatoes — "from boxed flakes to refrigerated prepared potatoes" — to find the best brand.…