Make the boxed cake mix according to the directions on the back. Pour the cake batter into a greased 9 x 13 inch pan and bake according to the box directions. When it is done take it out of the oven and let it cool. Once it is cool, use the handle of a wooden spoon to poke rows of holes in the cake.
Put raspberries into a food processor or blender. Pulse a couple times. If mixture seems to thick, add some water to thin it out. Pour the mixture over the cake and spread it out evenly. Let it soak in.
While you are letting the raspberry puree soak in, whisk together cold milk and the instant pudding mix in a bowl until it thickens. Fold in the Cool Whip. Spread it evenly over the top of the cake. Zest lemon over the top of the frosting. Place the fresh raspberries on top of the cake frosting. Refrigerate for at least 4 hours or overnight. You can decorate each piece with a small slice of lemon and fresh mint if you like. Keep cake refrigerated until serving.