Soak corn husks in warm water until pliable (About 2 hours).
Roast corn on grill or under broiler until lightly browned. Cut kernels from the cobs.
With a stand mixer, beat lard/shortening together with 1/4 cup butter until very light (5 to 6 minutes).
Mix masa and baking powder together.
Alternate beating masa flour mix and chicken stock to lard mixture with an electric mixer until all are fully incorporated and the mixture is spreadable. Fold in the roasted corn.
Take approximately 3 tablespoons of the masa and place in the middle of 1 corn husk. Fold the husk into the middle and wrap around the masa. Fold the ends in to make a parcel. Use strips of husk to make a tie and tie up the parcel.
Place tamales in a steamer and steam for 40 to 45 minutes. While tamales are steaming, heat a skillet to medium-high and add 2 tablespoons butter. Add shrimp and then sauce and cook until sauce is heated through and shrimp are pink. Serve 2 or 3 tamales (removed from husks) per serving with shrimp and sauce drizzled over.
When making the masa mix, take a small ball of the dough from the mixer and drop it into a glass of water. If it sinks, it still needs to be beaten more. If it floats, then it is mixed enough. These tamales freeze very well. This recipe is for one meal but I usually make up several batches and freeze them for later use. You will then have a quick week night meal.