48 Hours from Versailles to Provence

For your first overnight, how about Auxerre where you can easily reach Guedelon, where a castle is being built using medieval tools and methods. https://www.guedelon.fr/fr/ This should intrigue both adults and a ten year-old.
One other advantage to Auxerre is that Chablis is right down the road in the opposite direction, 14 kilometers/ 10 miles.
Of couse, Vézelay is just a bit to the south in Burgundy.

Versailles to Chartres to Chenancauex then across the Massif Central, a unique but off teh beaten path region of volcanic highlands (focused on Le Puy). It's essential that you get the relivant Michelin regional/ Green Guides. (I did not spell check the French names)

Or, costly toll roads to Grenoble with a loop thru the Alps to Provence.

Hi,
I would mix the two suggestions above for a more direct route. Chenonceaux is out of the way, and Auxerre is almost an hour away from Guedelon with some backtracking. So I would suggest :
Day 1: Versailles - sleep near Guedelon e.g. Saint Sauveur en Puisaye
Day 2: visit Guedelon then drive to Le Puy en Velay, a small town with a dramatic setting. The Lavaudieu Abbey is a worthwhile stop, close to Le Puy
Day 3: explore Le Puy then drive Le Puy-Aubenas-Vallon Pont d'Arc-Ardeche Gorge (extremely scenic drive)-wherever in Provence. Twisty but wide roads.

Given the distance, 2 nights is not a lot, but still allows for some exploration

I agree about sleeping in Saint Sauveur, but I think you need to stay more on the main track as 48 hours gives you less time than it appears, especially if you want to make stops along the way. Although an interesting route, you’ll spend too much time in the car going via the Massif Cental and Ardeche. That’s a wonderful trip for when you have more time. It’s 5 hours to Le Puy without stopping. Le Puisaye, where Guedelon is located, is already what we call deep into France.

With the 10 year-old in mind, from Saint Sauveur/ Guedelon go to Vezelay, and on south. Vienne just south of Lyon has a lot of Roman ruins and an excellent Roman museum. Or, there is the Solutre Rock https://www.burgundy-tourism.com/discover/must-see-tourist-attractions/INCONBOU000V50021Z/detail/macon/solutre-rock and pre-historic museum in the Macon area. And, there is also the Pre-historic caves in Burgundy https://www.grottes-arcy.net/, not exactly the Dordogne, but it does have the 25,000 year old hand print of a five year-old, which could interest your child.

Can’t help you with restaurants as my French husband makes u-turns through traffic whenever he spots a Routier, and I remember that’s where we ate in both Arcy-sur-Cure and near La Solutre.

You don’t say where you need to be in Provence, but that does make a difference with only 48 hours that include touring, eating, sleeping and driving. Provence, nowadays starts in Montelimar, and even further north according to some tourist information offices that are trying to attract visitors. So destination does matter.

I am going to be a little bit of a grump. You do not have enough time for the kind of delightful road trip you seek. To meander.

Versailles is exhausting, but will need to press on. If you visit Guedelion (which is not a bad idea), you will be tired but will need to press on for another 3 hours or so to get to within striking distance of Provence.

I'm not saying you can't do it, you have plenty of time to make the drive, but not for all the pokings about. You can certainly find some nice places to stop for lunch.

Here's a different plan. I won't say better, of course that is up to you. But of you return to Paris after Versailles, you can collapse on one of the many fast trains to Lyon (2 hrs) and then spend two nights--a full day plus--there. It is a fabulous place.

From there you can drive or take the train to Provence.