Preheat oven to 200°F. Place a wire rack inside a large rimmed baking sheet; set aside. Place cauliflower and water in a medium microwaveable bowl and cover with plastic wrap. Microwave on High until just tender, 2 to 4 minutes. Carefully remove plastic wrap and drain well. Let cool slightly, uncovered, at room temperature, for 5 minutes.
Transfer the drained cauliflower to the bowl of a food processor; pulse until broken into smaller pieces, about 3 pulses. Add eggs, flour, hot sauce, paprika, garlic powder, baking powder and ½ cup blue cheese; pulse until the cauliflower is finely chopped and the mixture is well combined, about 20 pulses. Remove the knife blade from the food processor and stir in the remaining ½ cup blue cheese.
Heat oil in a medium nonstick skillet over medium heat until shimmering. Working in 3 batches (about 6 to 7 fritters per batch), spoon 1 heaping tablespoon of cauliflower mixture into the hot oil and gently press into a 1 ½-inch-wide patty using a metal spatula. Cook until well browned on both sides, flipping once, about 2 minutes per side. Transfer to a paper-towel-lined plate using a metal spatula. Place the fritters on the prepared baking sheet and keep warm in the oven. Repeat the process with the remaining cauliflower mixture. Serve warm with sour cream, if desired.
