Heat a large (12-inch) skillet with high sides over medium heat until hot. Add the olive oil, making sure it spreads easily without sizzling or burning.
Add the shrimp to the skillet and sprinkle with chili powder and salt. Avoid overcrowding the pan; cook in batches if needed. Cook the shrimp for about 3-4 minutes total, flipping once or twice until they turn pink. Remove the shrimp from the skillet and set aside.
In the same empty skillet, add the butter and chopped onion, season lightly with salt, and cook over medium heat for about 3 minutes, stirring occasionally until the onion softens. Add the minced garlic and continue cooking for 2 more minutes, stirring occasionally and taking care not to burn the garlic. Reduce heat if necessary.
Stir in the cooked corn kernels and smoked paprika. Pour in the half-and-half and bring the mixture to a simmer. Add 3 ounces of the crumbled feta cheese and stir until the cheese melts smoothly into the sauce.
Squeeze the juice of half a lime into the creamed corn mixture. Return the cooked shrimp to the skillet and gently reheat everything together.
To serve, top with the remaining ½ cup of corn kernels, lime slices, and chopped fresh cilantro. If desired, sprinkle extra chili powder or paprika for added flavor.