Peel shallots and reserve skins. Chop shallots finely.
Cut kernels off the corn cobs and reserve cobs.
In a Dutch oven melt the butter and add the shallot skins and the shrimp shells. Saute about 3 minutes then add corn cobs, broth, water, parsley, thyme, rosemary and bay leaf. Bring to a boil, reduce heat and simmer for about 20 minutes. Strain stock through a sieve into a separate pot. Discard solids.
Heat remaining 2 tsps olive oil in a sauce pan large enough to hold the final dish. Add shallots and cook over medium heat about 3 minutes. Add the rice and cook another 2 minutes stirring. Add the wine and let it evaporate while continuing to stir.
Add ½ cup of stock and cook, stirring for a few minutes until stock is absorbed. Continue adding stock ½ cup at a time and stir while it is being absorbed. This will take about 30 minutes. Add the corn kernels with the last stock addition. Cook about 5 minutes, then add ¼ cup of the Parmigiano Reggiano and remaining ½ teaspoon salt and ⅛ teaspoon pepper.
Set risotto aside and keep warm while you sear the shrimp.