I made Princess Diana's favorite stuffed-eggplant dish and I can see why it was always on the royal dinner table

In his 2007 book "Eating Royally: Recipes and Remembrances From the Palace Kitchen," McGrady wrote that stuffed eggplant — or stuffed aubergine, as it's known in the UK — became a staple at Kensington Palace when Princess Diana lived there.

He wrote that it was "the princess's favorite dish," added that William and Harry would sometimes help assemble the meal.

"William and Harry came by the kitchen fairly often looking for a treat or to find out what was for dinner or even just to grab a piece of fruit. But every once in a while, they would try their hand at cooking," McGrady wrote. "'Can we make Mummy dinner, please?' they'd ask."

McGrady added in his book that the "boys would get very excited about putting that together" and "no matter that it looked like smashed eggplant when it was done, they served it proudly and the princess was thrilled."

You'll need:

• 2 small eggplants, each 6 inches long
• 4 tbsp olive oil, divided
• 1 large zucchini, coarsely chopped
• 1 large orange bell pepper, coarsely chopped
• 2 ribs celery, coarsely chopped
• ½ cup red onions, roughly chopped
• 1 ½ cups button mushrooms, sliced
• 1 large tomato, roughly chopped
• 2 slices of bacon, cooked crisp
• 1 cup grated mozzarella cheese
• 1 tbsp chopped fresh basil
• 2 tbsp grated Parmesan cheese

Slice each eggplant in half lengthwise, McGrady suggested in his cookbook. Then, use a knife to cut into the eggplants' white flesh and create a circle about ¼ inch from the skin all the way around. The cuts should be about one-inch deep, but be careful not to slice through the eggplants' outer skin.

Use that same knife to score — or make a cross — inside the circle to make it easier to remove the flesh once it's cooked. I had trouble removing the flesh later, so don't be afraid to make a few precise, deep cuts along the way.

Now, brush the eggplants with two tablespoons of olive oil and bake them on a tray in the oven for 15 to 20 minutes. (I accidentally dropped my olive-oil bottle and my eggplants got soaked, but they turned out fine — so don't be worried if you go a bit overboard with the olive oil.)

McGrady suggested flipping the eggplants over midway through cooking, so the bottoms don't become too brown. Remove the eggplants after 20 minutes, or when the flesh begins to soften.

I'd recommend starting this process before baking the eggplants or while they're in the oven since you'll have to cut several ingredients.

These ingredients will be thrown into a skillet and later added to the stuffed eggplants' shells, but there's no pressure to cut these all perfectly. It's all going to be stuffed into a shell at the end of the day.

I kept all the chopped ingredients in different containers during the process to keep organized, but you could group some of the ingredients that go into the pan at the same time together — like the mushrooms and red onions — to cut down on the number of dishes you'll need to wash later.

The recipe called for two slices of bacon, but I cooked four because I love the added crunch.

Season the ingredients with salt and pepper to your liking, then cook the vegetables until they begin to soften.

Then, add the tomato. Once properly mixed, take the skillet off the burner and let the mixture cool.

Let the skillet chill at room tempurature for eight to 10 minutes, then add the bacon, mozzarella cheese, and basil into the mixture.

I put extra mozzarella cheese into the mixture as a last-minute addition.

This was the most challenging part for me, so you're not alone if you struggled a bit!

Remove the flesh from the eggplant, but leave around ¼ of an inch on the bottom to create a shell. I used a knife to carefully carve out pieces of eggplant flesh until I carved something that resembled a shell.

Once the eggplant flesh is removed, chop it and add it to the vegetable mixture. McGrady didn't specify how large to chop each piece, so that's down to your personal preference. I made my eggplant chunks slightly large, so they were the star of the dish.

Then, you're going to spoon that mixture into the eggplant shells and sprinkle with Parmesan cheese.

McGrady said the eggplants are ready to eat once assembled, or people can reheat them in the oven for 15 minutes. He also said the eggplants could be refrigerated to eat later.

In his cookbook, McGrady wrote that Princess Diana would often "request that I leave an extra serving in the refrigerator for her to reheat on the weekend."

And I can see why. I'm actually eating one of my stuffed eggplants for lunch as I type this.

In addition to making delicious leftovers, this dish dispels the myth that healthy food can't be tasty or filling. The flavors of the vegetables in the stuffing blend wonderfully together, with the bell pepper, mozzarella cheese, and eggplant stealing the show. The pepper added a sweet note, while the cheese was a gooey addition that paid off. The only thing I'd do differently next time is add more bacon, but that's a personal preference.

Overall, as someone who has never been much of an eggplant fan — I'm partial to McGrady's stuffed bell-pepper recipe — I was pleasantly surprised by how much I liked this dish.

It's no wonder Princess Diana asked for extra servings.