Creamed Spinach And Leeks With Cheddar Recipe

Ingredients

• kosher salt
• 1 pound spinach leaves
• 4 tablespoons unsalted butter
• 2 tablespoons neutral-flavored olive oil
• 2 large leeks
• 3/4 teaspoon dry mustard
• 3/4 teaspoon plus a large pinch freshly ground white pepper
• 2 tablespoons Apple butter
• 1 tablespoon plus 1 1/2 teaspoons unbleached all purpose flour
• 1 3/4 cups whole milk
• 1 1/2 cups packed coarsely grated cheddar cheese