Preheat oven to 375° F.
Flatten your piece of puff pastry, and then roll it so it is about ⅛ inch - 3/16 inch thick. Set the small wheel of brie on the pastry just for reference, and then cut a circle of puff pastry large enough to wrap all the cheese entirely. Reserve the extra dough because you'll be using some of it later.
Brie rind is edible, so just leave it on. Mix a pinch or two of salt into the apricot preserves and spread it in a thick layer on top of the wheel of cheese.
Place the center of the circle of pastry over the center of the cheese, right on top of the jam. Gently press the pastry down the sides of the wheel of cheese. Turn the whole thing upside down and pleat and seal the pastry. Just press all the edges firmly together, but don't press straight down, or you'll mess up your layer of jam.
Turn the pastry covered wheel right-side up again. Put it on a parchment-lined baking sheet, and press down from the sides, just to make sure the cheese is sitting fairly level on the sheet. Cut a couple of heart shapes out of the extra pastry - or you could cut out your Valentine's initials or just some leaf or flower shapes. Use a little of the egg wash to "glue" these cut outs to the top of your wheel. Now, brush the entire wheel with a thin coat of egg wash. This will help it to get shiny and brown in the oven.
Bake for 20 minutes or so, until the pastry is a nice golden brown. Remove from the oven and let cool for a few minutes. Serve with crackers, toasted slices of baguette and maybe some fresh fruit.