Preheat oven to 350°F. Combine Honeycrisp apples, Granny Smith apples, brown sugar, cornstarch, butter, lemon juice, cinnamon and salt in a large bowl; stir until the apples are fully coated. Transfer the mixture to a 9-by-13-inch baking dish; cover with foil. Bake for 45 minutes. Remove the foil and stir the mixture. Bake, uncovered, until the apples are tender and caramelized, about 10 minutes more. Let cool for 5 minutes before serving.