Slice-and-Bake Oatmeal Raisin Cookies

• 1 1/4 cups all-purpose flour
• 3/4 cup whole wheat flour
• 1/2 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/2 teaspoon kosher salt
• 1/8 teaspoon ground nutmeg
• 1 cup (2 sticks) unsalted butter, room temperature
• 1 cup (packed) light brown sugar
• 1/2 cup sugar
• 2 large eggs
• 1 teaspoon vanilla extract
• 2 cups old-fashioned oats
• 2 cups raisins