Serves 12 to 14. If serving the cake within 24 hours, wrap in plastic wrap and store at room temperature. For longer storage, wrap with aluminum foil and freeze for up to 10 days. To thaw, remove foil and leave at room temperature for about 3 hours.
1 cup plus 2 Tbsp matza cake meal
1/4 cup plus 2 Tbsp potato starch
1 1/2 cups granulated sugar, divided
1/2 tsp salt
3/4 cup mashed ripe bananas (2 small or 1 large)
6 large eggs, separated
1 large egg
1/4 cup plus 2 TBs canola oil
2 tsps finely grated lemon zest
1 tsp pure vanilla extract
1. Center a rack in the oven and preheat to 325°F. Have ready an ungreased 10 x 4 1/4-inch tube pan, preferably with a removable bottom, and a long-necked bottle or large heat-resistant funnel for cooling the cake.
2. Sift together the cake meal, potato starch, 3/4 cup of the sugar and the salt into a large bowl. Make a well in the center and add the bananas, egg yolks, egg, oil, lemon zest and vanilla. Using a rubber spatula, incorporate the banana mixture with the dry ingredients, stirring until smooth, thick and well blended.
3. In the bowl of a stand mixer fitted with the whisk attachment, whip the egg whites on medium-low speed until soft peaks form, about 1 1/2 minutes. Increase the speed to medium and gradually add the remaining 3/4 cup sugar. Continue whipping until glossy-white, stiff-but-not-dry peaks form, about 2 minutes. Using a clean rubber spatula, fold 1 cup of the whipped whites into the cake batter to lighten it. Then fold in the remaining whites just until combined. Spoon the batter into the tube pan, spreading it evenly with the spatula.
4. Bake the cake until just golden, the top springs back when touched lightly and a round wooden toothpick inserted near the center comes out clean, 55 to 60 minutes. Remove the pan from the oven and immediately invert it over the long-necked bottle. Let cool completely, about 2 hours.
5. To remove the cake from a pan without a removable bottom, slip just the tip of a thin metal spatula or paring knife between the cake sides and the pan, slowly tracing the perimeter. Tilt the cake pan on its side and gently tap the bottom against a counter to loosen the cake. Rotate the pan, tapping it a few more times as you turn it, until the cake appears free from the sides of the pan. Place a wire rack on top of the cake, invert the pan and tap firmly on its bottom. Lift the pan from the cake.
(Note: I used a regular 9" springform cake pan, and the center was a bit mushy but it was still OK. A real springform tube pan would be preferable.)