1. Preheat oven to 350°F (175°C). Line a 10×15-inch jelly roll pan with parchment paper.
2. In a large bowl, beat eggs and granulated sugar until thick and pale. Stir in almond extract.
3. In a separate bowl, sift together flour, cocoa powder, baking powder, and salt. Gently fold the dry ingredients into the egg mixture until just combined.
4. Pour the batter into the prepared pan, spreading it evenly. Bake for 12-15 minutes or until the cake springs back when lightly touched.
5. While the cake is baking, lay a clean kitchen towel on the counter and dust it with powdered sugar.
6. Once the cake is done, immediately invert it onto the prepared towel. Carefully peel off the parchment paper.
7. Starting at one short end, gently roll the cake and towel together. Let it cool completely.
8. In a chilled bowl, whip the heavy cream, powdered sugar, and almond extract until stiff peaks form.
9. Carefully unroll the cake and spread the whipped cream evenly over the surface. Roll the cake back up without the towel.
10. Place the cake roll on a serving platter, seam side down. Chill for at least 1 hour.
11. Before serving, garnish with sliced almonds and a dusting of powdered sugar.