Step 1: Make the Roux. In a saucepan over medium heat, melt the butter. Stir in the flour until smooth.
Step 2: Add the Cream. Gradually add the heavy cream, stirring, and bring to a gentle boil. Cook and stir for 2 minutes, until thickened.
Step 3: Season and Add the Corn. Season with the mushroom seasoning, salt, and black pepper. Add the corn and heat through.
Step 4: Top and Broil. Transfer to a broiler-proof dish and sprinkle the shredded Parmesan in a layer over the top. Broil for 3-5 minutes, until a brown crust forms on top. Serve warm.