Mix crushed crackers with walnuts, cake mix, brown sugar and butter until crumbly.
Mix berries with lemon liqueur
In a large baking pan pour pineapple evenly in bottom of baking pan. Add berries and top off with the crackers, nut, cake and butter crumble. Distribute mixture evenly. Bake in a 350 degree oven for 50 minutes or unti, it's nice and bubbly. Serve with a dollop of whipped cream.