Make the pastry cream (even a day or two in advance) as instructed above in the linked recipe. Add unflavored gelatin as suggested. It makes the pastry cream sturdier. Alternatively, add about 1/2 recipe of lightly sweetened whipped cream. Just fold a little at a time into the pastry cream until it is sturdy enough to pipe. Save the remaining whipped cream to serve on the side or on top of each slice of this dessert.
Make the broiche according to the recipe instructions linked above; set aside to cool. Once cool, you may wrap in plastic wrap and then store in a zipper freezer bag and freeze if making in advance.
Slice the brioche in half. Pipe or spread the pastry cream or Bavarian cream and gently lay the top of the brioche on top.
Baste the top of the cake with simple syrup and sprinkle on the pearl sugar. (If you do not have pearl sugar, you can use lightly crushed sugar cubes.)
Slice and serve. Add a dollop of leftover whipped cream if desired.
https://glutenfreerecipebox.com/easy-gluten-free-tarte-tropezienne/