2 large russet potatoes (about 1 1/2 pounds)
1/2 cup gluten-free all-purpose flour, plus more for dusting
1 medium head cauliflower, chopped into florets (about 1 pound)
1/4 cup grated Parmesan
1 large egg yolk
Kosher salt and freshly ground black pepper
5 tablespoons unsalted butter, diced
2 tablespoons drained capers
1/4 cup fresh parsley, chopped
Salad, for serving