Apple Pie Bars

Ingredients

• 3 sticks unsalted butter, softened
• 3/4 cup sugar
• 3 cups all-purpose flour
• 1/2 teaspoon kosher salt
• 6 tablespoons unsalted butter
• 1/2 cup light brown sugar
• 12 granny smith apples (about 6 pounds)—peeled, cored and thinly sliced
• 1 tablespoon cinnamon
• 1/4 teaspoon freshly grated nutmeg
• 1/2 cup water, if necessary
• 3 cups quick-cooking oats
• 2 cups all-purpose flour
• 1 1/2 cups light brown sugar
• 1 1/4 teaspoons cinnamon
• 1/2 teaspoon baking soda
• 1/2 teaspoon kosher salt
• 3 sticks (12 ounces) unsalted butter, cut into 1/2-inch cubes and chilled
• 3/4 cup chopped pecans