If you don't have apricot jam, consider using other fruit jams such as peach, apricot preserves, or even a berry jam like raspberry or strawberry, which can provide a unique twist to your tartlets. For the apricot topping, fresh fruits like peaches or nectarines can stand in beautifully, adding a fresh seasonal element. You could also use other canned fruits, like pineapple or pears, ensuring that they are well-drained to avoid sogginess. If you want to stray from fruit toppings altogether, a drizzle of a decadent chocolate ganache or a layer of caramel can introduce a different flavor dimension while still being visually appealing.