Dissolve the dry yeast in warm milk and set aside for 10 minutes to activate. In a bowl, combine the flour, sugar, salt, egg, and vanilla. Add the milk and yeast mixture and knead until the ingredients are combined. Gradually add the butter, ensuring each piece is incorporated before adding the next, and continue kneading for 15 minutes to achieve a fluffy, elastic dough. Shape the dough into a ball, place it in a bowl, cover, and let it rise for 2-3 hours until doubled in volume. On a lightly floured surface, roll out the dough into a large sheet, about 45x45 cm. Spread the hazelnut praline over the dough, roll it up, cut it in half, and braid. Place in a well-buttered and floured rectangular mold, cover, and let it rise for about 40 minutes. Meanwhile, prepare the syrup by boiling the sugar, water, and lemon peel until the sugar dissolves, then simmer for 5 minutes and let cool. Bake the pastry in a preheated oven at 180°C (356°F) for 30-35 minutes. Remove, let cool slightly, then unmold and brush with the cooled syrup. Garnish with edible fresh flowers if desired