all-purpose flour (600 grams), salt (2.9 grams), unsalted butter (113 grams or 8 Tablespoons), melted, sour cream (237 grams), at room temperature, large eggs at room temperature, milk (59 ml), white sugar (5 grams), large russet potatoes (about 1.5 lb, or 680 grams), cottage cheese (170 grams), at room temperature, cream cheese (113 grams), at room temperature, Salt and pepper to taste, Caramelized onions (see below)