As an exception to most baking, make sure to use ingredients as cold as possible when making pastry: so cubed butter straight from the fridge and ice cold water. Keeping pastry cold helps avoid overworking the gluten and keep it relaxed to avoid shrinkage during baking.
Handle the pastry dough as little as possible throughout making. This is especially important when bringing it together, as overworking the gluten will lead to tough pastry.
When placing the pastry into the tin, try not to stretch the dough to make it fit. Stretching the dough may look fine once in the tin, but doing so will result in the dough shrinking back to its pre-stretched size and shape during baking, spoiling the look of the tart.
Chill the pastry again once rolled and shaped into the tin. Chilling the pastry a second time allows the gluten to relax again, helping it hold its shape better and not be tough once baked.
Spread the jam layer evenly over the base of the pastry, but not all the way to the edge. It will spread slightly over baking, so will look like it reaches the edges once baked. Doing this is one part of helping to prevent the jam bubbling up and over the frangipane, spoiling the look of the tart.
Piping the frangipane over the jam helps to get it spread out more evenly without disturbing the jam underneath too much, so I would definitely recommend piping if you can!
Once you have put the frangipane layer over the jam layer, use a knife or off set spatula to gently level it and ease it all the way to the edges of the pastry case. Sealing the jam is important so it does not bubble over and make a mess of the top of the Bakewell tart.
Swap out the raspberry jam for cherry or strawberry if you prefer, or that's what you have in. All will work!