Heat olive oil and butter in a large skillet over medium-high heat.
Add corn in an even layer and let it sit undisturbed for 3-4 minutes until charred.
Stir and char for another 2-3 minutes.
Stir in garlic and jalapeño for 1 minute until fragrant. Remove from heat and let cool slightly.
In a large bowl, whisk together mayo, sour cream, lime juice and zest, Tajín, and seasonings.
Fold in the charred corn, cotija, Monterey Jack, cilantro, and green onions.
Transfer to a baking dish and bake at 375°F for 18-20 minutes until bubbly and golden on top.
Finish with extra cotija, cilantro, a shake of Tajín, and one more squeeze of lime. Serve hot with tortilla chips.