1. Preheat the oven to 375°F or 190°C and line a baking sheet with parchment paper.

2. Grind the almonds in a food processor until they resemble coarse crumbs.

3. In a medium bowl, whisk together the confectioners sugar and egg whites until stiff peaks form.

4. Add the ground almonds to the egg mixture and gently fold until well combined.

5. Melt the butter in a small saucepan over low heat, then remove from heat and stir in the espresso or strong coffee.

6. Pour the coffee-infused butter mixture into the egg mixture and gently fold until smooth.

7. Spoon the mixture onto the prepared baking sheet, spreading it evenly to form a rectangle about 1/4 inch or 6mm thick.

8. Bake for 12-15 minutes, or until the edges are lightly golden, then remove from the oven and let cool completely.

9. Once the cake has cooled, spread the whipped cream over the top and sprinkle with chocolate shavings or chocolate chips.

10. Refrigerate the cake for at least 30 minutes before serving.