Preheat oven to 350 degrees. Spray a rimmed baking sheet (jelly roll pan) with cooking spray. Line with parchment paper, spray the parchment with more cooking spray and dust with 1 tablespoon of cocoa powder.
With an electric mixer beat the egg yolks with the granulated sugar on high speed until thick and pale yellow in color. Add 2 tablespoons cocoa powder, coffee and vanilla, beat in.
With clean beaters in a clean bowl beat the egg whites until stiff peaks form. Scoop about a quarter of the egg whites and stir into the yolk mixture. Fold in the rest of the egg whites in three additions. Spread the batter into the prepared pan and bake for 20 minutes. Let cool in the pan.
When cool, sprinkle 1 tablespoon cocoa powder over the top of the roll. Run a knife around the edges of the cake. Place a piece of parchment paper on top of the cake and place a sheet pan on top of that; invert to release the cake from the pan. Remove the parchment paper that is now on top of the cake.
Whip the heavy cream with the powdered sugar until soft peaks form. Fold in the toffee bits. Spread the cream over the top of the cake and roll, short end to short end. Dust with powdered sugar if desired.
*Left over coffee from the morning or day before if fine