Prepare a 13 x 9-inch glass pan.

Mix graham cracker crumbs, melted butter, and powdered sugar in a bowl.

Reserve 1/2 cup of the crumb mixture for topping.

Press the remaining crumb mixture into the bottom and sides of the prepared pan to form the crust.

Dissolve lemon jello in boiling water in a separate bowl.

In a large mixing bowl, cream together softened cream cheese and sugar until smooth.

Add vanilla and lemon flavoring to the cream cheese mixture and blend well.

Gently fold in the chilled evaporated milk into the cream cheese mixture.

Pour the lemon jello mixture into the cream cheese mixture and mix until well combined.

Pour the filling over the prepared graham cracker crust.

Sprinkle the reserved graham cracker crumb mixture over the top of the filling.

Refrigerate for at least 30 minutes, or until set, before serving.