Sheet Pan Apple Crumble

Ingredients

• 1 1/2 cups all-purpose flour
• 7 medium baking apples, such as Gala or Fuji, peeled, cored, and cut into 1/4-inch slices
• 2 teaspoons ground cinnamon, divided
• 1 1/8 teaspoons kosher salt, divided, plus more to taste
• vanilla ice cream, optional, for serving
• 1 1/2 cups light brown sugar, packed and divided
• 1 tablespoon fresh lemon juice
• 2 sticks unsalted butter, melted and divided
• 2 cups old-fashioned rolled oats