Preheat oven to 400F.
Remove husks and strings from corn cob, then rub it all over with softened butter. Season with salt and pepper. Place on parchment or foil-lined sheet pan and roast 30 minutes, rotating it every 10 mins as it cooks.
Remove the corn from the oven, let cool slightly, and use a sharp knife to remove the kernels from the cob.
Combine corn kernels with jalapeño, cheese, garlic, scallions, and cilantro in a bowl. Then add the egg and salt and stir to evenly incorporate. Add the flour last, starting with 3 TBSP and adding an additional 1 TBSP if it doesn't seem like it's holding together. The finished corn fritter "batter" should be fairly loose but should mostly stick together when you scoop it.
Heat a generous glug of olive oil in a skillet over medium heat. Test if the skillet is hot enough by dropping one kernel of corn into the skillet — if it doesn't immediately start bubbling, the skillet isn't hot enough.
Use a ¼ or ⅓ cup scoop to transfer dollops of the batter into the skillet. Use a spatula or the bottom of the measuring cup to press down on the top of the fritter and flatten them to about ¼" tall. Cook approx 3-4 mins per side. Remove to a paper towel to drain.
While the fritters cook, mash an avocado with lime juice, salt, pepper, thinly sliced scallion, and cilantro in a small bowl. Dollop on top of corn fritters to serve.