For the dough, add the sugar, dry yeast, milk, salt, flour, egg, egg white, and butter to a bowl and knead until a smooth dough forms. Cover the dough and let it rise for about 1 hour.
To make the filling, add the cream cheese, yogurt, egg white, corn starch, vanilla bean, and simple syrup to a bowl and stir until combined.
Roll out the dough and place a pot lid in the middle. Cut the edge of the dough into strands, which will become the "petals" of your pie flower. To make the "petals", work with 3 at a time: twist the middle one, then press together the two on either side at the top. Repeat for the remaining strands, then let the dough rise for another 15 minutes.
Preheat the oven to 350°F. Place the dough flower on a baking sheet lined with parchment paper and prick the circle in the middle all over with a fork.
Spread the cream cheese filling on the circle of dough and push blueberries into it. Smooth out the cream, brush the egg wash over the edge of the dough, transfer the pan to the oven, and bake for 40 minutes. When it's ready, take it out and let it cool. Garnish the tart with grated chocolate and enjoy!