Preheat the oven to 400 degrees F. Line a large baking sheet with parchment paper.

In a medium bowl, add strawberries and sugar and gently stir to coat the strawberries with sugar to bring out the strawberry flavors and juiciness. Set aside for later.

In the bowl of an electric mixer (or feel free to use a hand mixer), add the softened butter, sugar and egg yolk and beat on high for 1 minute until well combined. Add the almond flour and almond extract and beat again on high for another 30 seconds until mixture is light and fluffy. Set aside.

Lay the sheet of thawed puff pastry on a clean surface lightly dusted with flour and roll out to an approximately 9x13 inch sheet (sometimes they shrink when frozen). Cut the puff pastry into 9 equal rectangles, then lay each piece on the parchment-lined baking sheet, leaving a ½-inch space between each piece. Poke each piece a few times with a fork.

Add 1 heaping tablespoon of the almond filling to the middle of each puff pastry and evenly spread towards edges, making a ½-inch border around the edge. Top the filling of each pastry with 3-4 strawberry slices.

In a small bowl, whisk the egg with a fork and use a pastry brush to brush on the edges of each puff pastry piece. This will create a nice golden brown crust when baked. Finally, evenly sprinkle almond slices on each piece.