Place slivered almonds in a dry pan over medium high heat. Keep a constant eye on them, swirling to ensure even toasting. Remove when almonds are golden brown and set aside to cool.
Preheat oven to 400° F. Prepare a baking sheet with nonstick spray. Unfold puff pastry onto lightly floured board and cut into 9 equal squares. Place on lightly greased baking sheet and bake for 12-15 minutes.
While puff pastry is baking, pour heavy cream into large bowl and start to whip. While whipping, slowly pour cocoa, powdered sugar, and vanilla extract into bowl. Scrape sides and continue to whip until stiff peaks form.
To assemble, cut baked puffed pastry in half horizontally to make a top and a bottom. Spoon chocolate cream onto bottom, top with strawberries and then other half of puff pastry. Top with more cream and toasted almonds.