Line the base of a 20cm springform tin with foil. Spray the base and sides lightly with canola oil spray.
Place the biscuits and the margarine in a food processor and process until well combined. (Alternatively, crush the biscuits in a plastic bag with a rolling pin, and then mix through the melted margarine).
Put the mixture into the springform tin and press mixture down well and evenly over the base. (Use the base of a clean jar, pressing firmly on the biscuit mix, to give an even surface). Refrigerate while you prepare the filling.
Heat the lemon juice and sprinkle with the gelatine. Stir well with a fork. Cool. Whisk the ricotta cheese, Philadelphia cheese, Equal Spoon for Spoon and lemon rind together until smooth. Swish the gelatine mixture. Beat the egg white until stiff peaks form, then fold into the cheese mixture.
Pour evenly over the crumb crust, smooth the top evenly.
Refrigerate until set.