Hey Denise. Thanks for this. The thing about “wing it” recipes is that you can try lots of variations. So great excuse to go wild!
And about cooking first. Several recipes suggest taking the whipping cream and the sliced potatoes and cooking stove top till just barely soft. I have tried this and then used my cooking pot to do the roasting too. It did and didn’t save time. Yes on bake time, no on my prep time. No on presentation, because, pot.
I know your Alfredo sauce recipe, well a version of it. And I love it! You made me hungry reminding me of it!
TBH, my best result with Gratin D has been to go the traditional route, but use only one quart of cream(so no leftover cream to waste) and eye-balling the right amount of potatoes so the cream just covers the top leaving most of cheese layer exposed. I have found that gives me the closest approximation to the tators at Bistrot D’Henri.
Hope this helps.