Preheat oven to 180 degrees C. Butter a 23cm springform cake tin and sprinkle the bottom with 1/2 the biscuit crumbs.
In a food processor, combine the ricotta and sour cream until smooth. Add egg yolks and 1/2 cup sugar and process well. Add flour, vanilla and almond extracts, zest and pinch of salt. Process until blended.
With an electric mixer, beat the egg whites and cream of tartar to the soft peak stage. Add remaining sugar and beat to stiff peaks. Fold 1/3 of the eggs into the ricotta mixture in a mixing bowl, then fold in another 1/3, and then the last 1/3.
Placed batter in the cake tin and sprinkle with remaining crumbs. Bake 40 minutes until browned and almost set. Let cool.