Step 1: Prepare the Almond Frangipane Filling

1. In a mixing bowl, combine almond flour, softened butter, and granulated sugar.
2. Beat in the egg, vanilla extract, and almond extract until smooth and creamy.
3. Add 1 tablespoon of milk and mix well. Set aside.

Step 2: Prepare the Puff Pastry

1. Preheat your oven to 375°F (190°C).
2. Lightly grease a muffin tin or line it with parchment paper.
3. Roll out the thawed puff pastry sheet on a lightly floured surface.
4. Cut the pastry into 12 equal squares (each should be about 3×3 inches).

Step 3: Assemble the Muffins

1. Place a square of puff pastry into each muffin cup, gently pressing it down to form a cup shape.
2. Brush the inside of each pastry with melted butter and sprinkle with a little sugar.
3. Spoon 1 tablespoon of the almond frangipane filling into each muffin cup.
4. Sprinkle sliced almonds on top.

Step 4: Bake the Muffins

1. Bake in the preheated oven for 22-25 minutes, or until the tops are golden brown and crispy.
2. Remove from the oven and let cool for 5 minutes before transferring to a wire rack.

Step 5: Finishing Touches

1. Once the muffins are completely cool, dust with powdered sugar for an elegant finish.
2. Serve warm and enjoy!