In a medium saucepan, combine the raisins, vinegar, bay leaf and salt. Simmer for 5-10 minutes, or until the brine has reduced slightly.
Cut 1 1/2 heads of cauliflower into small-ish florets. Toss the florets, oil and plenty of salt. Spread on two parchment-lined baking sheets. Roast at 425F for about 25 minutes, stirring once or twice, until the cauliflower is crispy-skinned and browned. Alternatively, you can pan-sear the cauliflower (this works well if you're running short on time).
Mix 2 T lemon juice with 1 T vinegar. Whisk in mustard. While whisking constantly, slowly pour in the oil. When your mixture is creamy and emulsified, whisk in the crème fraîche. Season with salt.
To a large serving bowl, add the remaining grapes and cheese. Shave the remaining cauliflower on a mandoline into the bowl. Add the roasted cauliflower. Strain the pickled raisins and grapes (you can reserve the liquid to make salad dressing in the future!) and add them to the bowl. Add the almonds and mix it all together. Dress the salad with the vinaigrette, going slowly as to not overdress. Serve warm.
Adapted slightly from Sarah Jampel via Food52.