In a saucepan, simmer the grated corn and juices with the 1/4 cup of milk over moderate heat, stirring, until thick, 4 minutes. Season with salt and pepper and fold in the pecan butter; keep warm.
In a large, deep skillet, melt 4 tablespoons of the butter. Add the ham and cook over moderately high heat, stirring, until lightly browned, about 5 minutes. Add the onion, snap peas and corn, season with salt and pepper and cook until crisp-tender, about 5 minutes. Add the shrimp and cook, stirring, until they just begin to curl, about 3 minutes. Add the lager and bring to a boil. Simmer, stirring frequently, until the shrimp are cooked through and the liquid is slightly reduced, about 3 minutes. Swirl in the remaining 2 tablespoons of butter.
Whisk a little milk into the grits so it's the consistency of polenta; heat until warm. Spoon the grits into shallow bowls, top with the shrimp sauté and serve at once.