Combine oats, flour, brown sugar, and salt in a shallow pan for the crust.

Add melted butter to the crust mixture and mix thoroughly.

Bake the crust at 350°F for 10 minutes.

Soften gelatin in cold water.

In a saucepan, combine egg yolks, sugar, lemon rind, and lemon juice.

Cook over low heat until the mixture boils.

Remove the mixture from the heat, add softened gelatin, and stir until dissolved.

Allow the lemon-gelatin mixture to cool thoroughly.

Beat egg whites until foamy.

Gradually add sugar to the egg whites while beating until stiff peaks form.

Gently fold the cooled gelatin mixture into the beaten egg whites.

Put half of the baked crumb crust in a pan.

Add the lemon-gelatin filling on top of the crust.

Top the filling with the remaining crumb crust.

Chill the dessert until it is set.