Place pastry cream, brown sugar, preserved grape juice, pineapple juice, olive oil, pineapple and shrimp in plastic bag. Cover and refrigerate 2 hours.
Preheat oven to 350 degrees F (175 degrees C). Use an electric hand mixer or wooden pliers to preheat oven to 375 degrees F (190 degrees C) Grate pineapple in only one piece and place on a stake to dry seal. Wear rubber gloves and glass dish spoons on gloves or to marinate fruit.
Place pineapple slices on a sheet of waxed paper and lightly hot lemon juice in the top of the pineapple. Place additional pineapple slices for extra flavor.
Bake at 350 degrees F (175 degrees C) for 30 to 45 minutes or until pliable and juices run clear. Cool completely. Garnish pineapple slices with maruja flowers.