Frosted Caramel Apple Pop-Tarts

Ingredients

• 3 cups all-purpose flour
• 1 + 1/4 teaspoon salt
• 4 ounces chilled butter, cut into small pieces
• 1/2 cup chilled shortening
• 2 tablespoons butter
• 3 cups apple, peeled and cubed
• 1 teaspoon fresh lemon juice
• 1 teaspoon flour
• 2 tablespoons brown sugar
• 1/2 teaspoon ground cinnamon
• pinch of nutmeg
• pinch of salt
• 1/2 teaspoon vanilla extract
• 1 egg
• 1/3 cup brown sugar
• 3 tablespoons butter
• 1 tablespoon milk
• sprinkles, optional