Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a bowl, whisk together flour, baking powder, and salt.
In another bowl, beat egg yolks and sugar until thick and pale. Add champagne and mix well.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
In a separate bowl, beat egg whites until stiff peaks form. Gently fold into the batter.
Spread the batter evenly on the prepared baking sheet. Bake for 12-15 minutes.
Remove from oven and let cool slightly. Roll the cake in a towel dusted with powdered sugar. Let cool completely.
For the filling, whip the heavy cream until soft peaks form. Add champagne and powdered sugar, and continue to whip until stiff peaks form.
Unroll the cake, spread the filling evenly, and roll it back up. Chill for at least 1 hour before serving.