Make the almond cream: in a medium saucepan combine the Blanched Ground Almonds, Granulated Sugar, and Water with the Cinnamon Stick and a strip of Lemon Peel.
Bring the mixture to a gentle simmer over medium heat, stirring frequently, and cook until it thickens into a spreadable paste (about 10–15 minutes); remove and discard the cinnamon stick and lemon peel.
Temper and enrich the filling by stirring a few spoonfuls of the hot almond mixture into the Egg Yolks to warm them, then return the yolk mixture to the saucepan off the heat and stir until fully combined; let cool to room temperature, then chill briefly so it firms slightly.
Preheat the oven to 200°C (400°F) and line a baking sheet with parchment.
On a lightly floured surface, roll the All-Butter Puff Pastry into a rectangle about 3–4 mm thick and cut into roughly 10 x 8 cm rectangles (or your preferred size).
Place a heaped teaspoon (or slightly more) of the chilled almond cream in the center of half the pastry rectangles, leaving a border around the edges.
Brush the edges with a little beaten Egg, top with another pastry rectangle and gently press the edges to seal; crimp with a fork to ensure they are well sealed and prick the top once or twice to vent.
Brush the tops with more of the beaten Egg, then sprinkle generously with Granulated Sugar mixed with a little Ground Cinnamon.
Bake the travesseiros for 15–25 minutes, until puffed and deep golden brown, rotating the pan halfway through for even coloring.
Allow the pastries to cool on a rack for a few minutes so the filling sets slightly; serve warm or at room temperature.
