Preheat the oven to 450°F (230°C). Line a baking sheet with parchment paper.
2. Step
Bring a large pot of salted water to boil. Add the corn and boil for 5–7 minutes, until the kernels are tender and bright yellow. Use tongs to remove the corn and set aside.
3. Step
In a small saucepan, combine the butter and brown sugar. Cook over medium-low heat, whisking together as the butter melts. Whisk in heavy cream and fish sauce. Let bubble for 1–2 minutes. Remove the pot from the heat and stir in the lime zest and juice.
4. Step
Place the corn on the prepared baking sheet. Brush the corn on all sides with the caramel.
5. Step
Bake the corn for 10 minutes, using tongs to rotate the cobs every few minutes and basting with more caramel, until caramelized and browned.
6. Step
Serve corn with lots of chopped Thai basil and halved limes.
