1. Prepare the corn butter: Overcook the corn by boiling for 15 minutes. Remove from the water and let cool completely. Slice the kernels and scrape the milk from the cobs; blend together with the one stick of softened butter in a food processor. Add a hearty pinch of salt, blend again, taste, and adjust accordingly. Refrigerate until assembly.
2. Place the potatoes in a pot and fill it halfway full of water, making sure the potatoes are covered with water. Bring to high heat on the stove top. Boil until the potatoes are tender and cooked completely. Drain and set aside.
3. Right before you are ready to serve the canapé, halve the potatoes and chop the parsley.
4. Cut half of the remaining stick of butter into a large sauté pan and turn to medium-high heat. Once the butter has melted, add the shrimp to the pan and half of the Old Bay Seasoning. Toss together and cook until the shrimp is firm and opaque. Remove from the heat and roughly chop the shrimp. Dust with the remaining Old Bay Seasoning.
5. With the remaining butter and a hot griddle, place the potatoes, cut side down, onto the griddle, and crisp to golden brown.
6. Finally, assemble the canapé: Generously smear the cut sides of the potatoes with corn butter, top with a forkful of chopped shrimp, and top with the parsley. Serve right away.