Preheat the oven to 350°F. Line the bottom of a 9x3” cheesecake or springform pan with parchment.
Spray the middle of the paper only. Do not spray the sides. Set aside.
Melt the butter and set aside to cool.
Add the eggs, sugar and lemon zest to the mixing bowl. Beat until very, very thick , almost white and the mixture falls in ribbons from the beater.
Sift half the flour over the egg mixture and fold in about ¾ of the way. Repeat with the remainder of the flour.
Add about 1 cup of the batter to the melted butter. Whisk vigorously to form an emulsion.
Pour the emulsion back into the main batter and fold in.
Pour the batter into the prepared pan, smoothing as necessary.
Bake for about 23 to 28 minutes until a tester comes out cleanly and the cake bounces back when lightly touched in the middle.
Cool completely in the pan.
To release, go around the inside edge with a small, flexible metal spatula. Make sure the spatula stays to the side of the pan and not the side of the cake.
Remove the side. Turn the cake upside down, remove the bottom and the parchment paper.
Turn right side up. If not using immediately, freeze the cake, wrap it well and then freeze for several months. Partially thaw at room temperature to use.