Cut the kernels off the cobs, using a Bundt pan if available. You want to have 4 cups corn, divided into 3 cups and 1 cup. Stick the cobs back on the Bundt pan one by one, and firmly scrape downward with back of butter knife to remove any pulp remaining on cob. Put the 3 cups of corn kernels plus the pulp in a blender.
Process corn and pulp on low speed until thick puree forms, about 30 seconds. With blender running, add 1/2 cup hot water. Increase speed to high and continue to process until smooth, about 3 minutes longer. Pour puree into a fine-mesh strainer set over large bowl. Using back of a ladle, push puree through strainer, extracting as much liquid as possible. You want to have about 1 1/2 – 2 cups corn liquid. Discard solids.
Melt butter in large Dutch oven over medium heat. Add shallot, salt, garlic and pepper and cook, stirring frequently, until softened but not browned, about 1 minute. Add rice and thyme and cook, stirring frequently, until grains are translucent around edges, 2 to 3 minutes.
Stir in 4 1/2 cups hot water. Reduce heat to medium-low, cover, and simmer until liquid is slightly thickened and rice is just al dente, 16-19 minutes, stirring twice during cooking.
Add corn liquid and continue to cook, stirring gently and constantly, until risotto is creamy and thickened but not sticky, about 3 minutes longer (risotto will continue to thicken as it sits). Stir in Parmesan and remaining 1cup corn kernels. Cover pot and let stand off heat for 5 minutes. Stir in crème fraiche, chives and lemon juice. Season with salt and pepper to taste. Adjust consistency with remaining 1/2 cup water as needed. Serve immediately.
