(1) The dessert is still delicious with ½ cup granulated sugar in the filling instead of ⅔ cup, and if your sweet tooth is a bit more sensitive than mine, you might find you prefer that amount of sugar. If you’re using very tart baking apples, though, I might recommend the ⅔ cup. (2) You can easily play around with the amount of creme fraiche and sour cream here. A full cup of creme fraiche (omitting the sour cream) is decadently rich but delicious; the original recipe calls for 1 cup of sour cream only, which also works. I think you could even substitute some of it with Greek yogurt and have a good outcome, though I haven’t tried it. (3) For a more traditional crumble topping, as opposed to the lacey, crackly top shown, decrease the amount of butter to 4 tablespoons (½ stick or about 66 grams). A handful of oats wouldn’t hurt anyone, either.